arm64: ptrace: map SPSR_ELx<->PSR for compat tasks

The SPSR_ELx format for exceptions taken from AArch32 is slightly
different to the AArch32 PSR format.

Map between the two in the compat ptrace code.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Fixes: 7206dc93 ("arm64: Expose Arm v8.4 features")
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Suzuki Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>