🔨 Drop extraneous build flag (#23862)

ini/stm32f4.ini

 platform_packages = ${stm_flash_drive.platform_packages}
 build_unflags     = -DUSBD_USE_CDC
 build_flags       = ${stm_flash_drive.build_flags}
-                    -DSTM32F446_5VX -DUSE_USB_HS_IN_FS
-                    -DUSE_USBHOST_HS -DUSBD_IRQ_PRIO=5
-                    -DUSBD_IRQ_SUBPRIO=6
+                    -DUSE_USB_HS_IN_FS -DUSE_USBHOST_HS
+                    -DUSBD_IRQ_PRIO=5 -DUSBD_IRQ_SUBPRIO=6
                     -DUSBD_USE_CDC_MSC
 
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