[X86][CodeGen] Set mayLoad = 1 for LZCNT/POPCNT/TZCNTrm_(EVEX|NF)

Promoted and NF LZCNT/POPCNT/TZCNT were supported in #79954.
B/c null_frag is used in the patterns for these variants, tablgen can
not infer mayLoad = 1 for them.

This can be tested by MCA tests, which will be added after
-mcpu=<cpu_with_apx> is supported.