[llvm] [AArch64] Allow splitting bitmasks for EOR/ORR. (PR #150394)

[via llvm-commits]

AZero13 wrote:

For example, if we wanted to materialize a number that had the form: 0xFFFFFFFF`FFFFFXXX,

We can do sub Xd, xzr, #imm12

https://github.com/llvm/llvm-project/pull/150394