Make Prusa-Firmware MK3 3.14+ compatible with older printers

[pdxtigre]

Hello,

I'd like to suggest that we should remove the check for older printer types here moving forward and use only

current_position[Z_AXIS] = Z_MAX_POS + 2.0;

Prusa-Firmware/Firmware/Marlin_main.cpp

Lines 2241 to 2246 in 65fde95

 if (PRINTER_TYPE == PRINTER_MK3) { 
 	current_position[Z_AXIS] = Z_MAX_POS + 2.0; 
 } 
 else { 
 	current_position[Z_AXIS] = Z_MAX_POS + 9.0; 
 } 

Same here:

current_position[Z_AXIS] = Z_MAX_POS-3.f;

Prusa-Firmware/Firmware/ultralcd.cpp

Lines 2856 to 2864 in 65fde95

 calibrated: 
     // Let the machine think the Z axis is a bit higher than it is, so it will not home into the bed 
     // during the search for the induction points. 
 	if ((PRINTER_TYPE == PRINTER_MK25) || (PRINTER_TYPE == PRINTER_MK2) || (PRINTER_TYPE == PRINTER_MK2_SNMM)) { 
 		current_position[Z_AXIS] = Z_MAX_POS-3.f; 
 	} 
 	else { 
 		current_position[Z_AXIS] = Z_MAX_POS+4.f; 
 	} 

The reason is that it will make this firmware compatible with even older Prusa MK2. Let me know if that would cause any incompatibility issues.

So far, I've compiled and run this codebase on Prusa MK2 upgraded to MK25S with out any problem with those changes.

[3d-gussner]

@pdxtigre Thanks for the report. Please see #4604
The hard coded values are a bit of pain. But these values above are valid as the extruder bodies and other parts of MK2, MK2.5, MK2.5S, MK3 and MK3S differ a bit.
So you can't just set "one" value for these different printers, as mentioned above the hard coded values aren't helping.

[3d-gussner]

Closing as it is a duplicate