[RISCV] Don't make Zacas or Zabha imply A in RISCVISAInfo.cpp

Zabha and Zacas are both documented as depending on Zaamo. I'm
hesitant to make them imply Zaamo instead.

So remove the implication and replace with a check that either
A or Zaamo is enabled.

GitOrigin-RevId: d9715c698c4940e65e9bd036e22fb5cab3aa2c6f
1 file changed