[PowerPC] redesign the target flags (#69695)

12 bit is not enough for PPC's target specific flags. If 8 bit for the
bitmask flags, 4 bit for the direct mask, PPC can total have 16 direct
mask and 8 bitmask. Not enough for PPC, see this issue in
https://github.com/llvm/llvm-project/pull/66316

Redesign how PPC target set the target specific flags. With this patch,
all ppc target flags are direct flags. No bitmask flag in PPC anymore.

This patch aligns with some targets like X86 which also has many target
specific flags.

The patch also fixes a bug related to flag `MO_TLSGDM_FLAG` and `MO_LO`.
They are the same value and the test case changes in this PR shows the
bug.