[AMDGPU] Fix GCNUpwardRPTracker. (#71186)

Fixed:

1. Maximum register pressure calculation at the instruction level. 
Previously max RP included both def and use of registers of an
instruction. Now maximum RP includes _uses_ and _early-clobber defs_.

2. Uses were incorrectly tracked and this resulted in a mismatch of
live-in set reported by LiveIntervals and tracked live reg set when the
beginning of the block is reached.

Interface has changed, moveMaxPressure becomes deprecated and
getMaxPressure, resetMaxPressure functions are added. reset function
seem now more consistent.