kselftets/arm64: Use flag bits for features in fp-ptrace assembler code

The assembler portions of fp-ptrace are passed feature flags by the C code
indicating which architectural features are supported. Currently these use
an entire register for each flag which is wasteful and gets cumbersome as
new flags are added. Switch to using flag bits in a single register to make
things easier to maintain.

No functional change.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20241112-arm64-fp-ptrace-fpmr-v2-1-250b57c61254@kernel.org


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>