Use BED_MAXTEMP for PTC_MAX_BED_TEMP (#17061)

Marlin/Configuration_adv.h

   #if ENABLED(PROBE_TEMP_COMPENSATION)
     // Max temperature that can be reached by heated bed.
     // This is required only for the calibration process.
-    #define PTC_MAX_BED_TEMP 110
+    #define PTC_MAX_BED_TEMP BED_MAXTEMP
 
     // Park position to wait for probe cooldown
     #define PTC_PARK_POS_X 0.0F