GETPC: Do not manipulate the 32bit return address

We can do that offline, saving over 30 bytes of instructions.

Firmware/asm.h

@@ -19,9 +19,6 @@ static inline void GETPC(uint32_t* v)
   ((uint8_t*)v)[1] = b;
   ((uint8_t*)v)[2] = c;
   ((uint8_t*)v)[3] = 0;
-
-  // go back 1 instruction before rcall
-  *v = (*v - 2) * 2;
 }
 
 #endif