🩹 Use `#pragma once` in pins files

Marlin/src/pins/mega/pins_PICA.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * Arduino Mega with PICA pin assignments

Marlin/src/pins/mega/pins_PICAOLD.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 #define HEATER_0_PIN                          9   // E0
 #define HEATER_1_PIN                         10   // E1

Marlin/src/pins/ramps/pins_K8600.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * VERTEX NANO Arduino Mega with RAMPS EFB v1.4 pin assignments.

Marlin/src/pins/ramps/pins_TT_OSCAR.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 #include "env_validate.h"
 

Marlin/src/pins/sam/pins_CNCONTROLS_15D.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * CNControls V15 for HMS434 with DUE pin assignments

Marlin/src/pins/sam/pins_RURAMPS4D_11.h

  *
  * Ported sys0724 & Vynt
  */
+#pragma once
 
 /**
  * Arduino Mega? or Due with RuRAMPS4DUE pin assignments

Marlin/src/pins/sam/pins_RURAMPS4D_13.h

  *
  * Ported sys0724 & Vynt
  */
+#pragma once
 
 /**
  * Arduino Mega? or Due with RuRAMPS4DUE pin assignments

Marlin/src/pins/stm32f1/pins_CREALITY_V4.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * Creality 4.2.x (STM32F103RET6) board pin assignments

Marlin/src/pins/stm32f1/pins_CREALITY_V4210.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * CREALITY 4.2.10 (STM32F103) board pin assignments

Marlin/src/pins/stm32f1/pins_CREALITY_V427.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * CREALITY v4.2.7 (STM32F103) board pin assignments

Marlin/src/pins/stm32f1/pins_CREALITY_V431.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * CREALITY v4.3.1 (STM32F103) board pin assignments

Marlin/src/pins/stm32f1/pins_CREALITY_V452.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * Creality v4.5.2 (STM32F103RET6) board pin assignments

Marlin/src/pins/stm32f1/pins_CREALITY_V453.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * Creality v4.5.3 (STM32F103RET6) board pin assignments

Marlin/src/pins/stm32f1/pins_CREALITY_V45x.h

  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  *
  */
+#pragma once
 
 /**
  * Creality v4.5.2 and v4.5.3 (STM32F103RET6) board pin assignments

Marlin/src/pins/teensy2/pins_TEENSYLU.h

  * You should have received a copy of the GNU General Public License
  * along with this program.   If not, see <https://www.gnu.org/licenses/>.
  */
+#pragma once
 
 /**
  *  Rev C  2 JUN 2017