arm64: sysreg: Add FPCR and FPSR

arm64: sysreg: Add FPCR and FPSR

Add sysreg definitions for FPCR and FPSR.

Some versions of LLVM will refuse to assemble accesses to FPCR and FPSR
unless the "fp" arch extension is enabled, which we don't currently do
for read_sysreg() and write_sysreg(). In general, handling feature
dependencies would complicate read_sysreg() and write_sysreg(), and it's
simpler to use read_sysreg_s() and write_sysreg_s() instead, requiring
sysreg definitions.

The values used can be found in ARM ARM issue M.b:

  https://developer.arm.com/documentation/ddi0487/mb/

... in sections:

* C5.2.8 ("FPCR, Floating-point Control Register")
* C5.2.10 ("FPSR, Floating-point Status Register")

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oupton@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>