kselftest/arm64: Log SVCR when the SME tests barf

kselftest/arm64: Log SVCR when the SME tests barf

On failure we log the actual and expected value of the register we detect
a mismatch in. For SME one obvious potential source of corruption would be
if we had corrupted SVCR since changes in streaming mode will reset the
register values, log the value to aid in understanding issues.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20231205-arm64-kselftest-log-svcr-v1-1-b77abd9ee7f3@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>