Increase SCURVE cycle count for unoptimized cortex-m0

Cortex-M0 doesn't have 32bitx32bit=64bit multiplication instructions
and can not use optimized path.

Increasing to actual cycle count of 500 to hopefully improve
stability of board as well as a form of documentation that people
should consider disabling SCURVE feqature until the code is optimized
for cortex-m0;

Marlin/src/module/stepper.h

@@ -87,7 +87,11 @@
 
   // S curve interpolation adds 40 cycles
   #if ENABLED(S_CURVE_ACCELERATION)
-    #define ISR_S_CURVE_CYCLES 40UL
+    #if defined(STM32G0B1xx)
+      #define ISR_S_CURVE_CYCLES 500UL
+    #else
+      #define ISR_S_CURVE_CYCLES 40UL
+    #endif
   #else
     #define ISR_S_CURVE_CYCLES 0UL
   #endif