[clang] [llvm] [ARM] Armv8-R does not require fp64 or neon. (PR #88287)

[Chris Copeland via cfe-commits]

chrisnc wrote:

Another option is to include `FeatureFPARMv8_D16_SP` in `ARMv8r`. The R-profile supplement of the Arm manual does say that this is a minimum feature requirement (as opposed to just being a variant of the R52).

https://github.com/llvm/llvm-project/pull/88287