kselftest/arm64: parse POE_MAGIC in a signal frame

kselftest/arm64: parse POE_MAGIC in a signal frame

Teach the signal frame parsing about the new POE frame, avoids warning when it
is generated.

Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240822151113.1479789-29-joey.gouly@arm.com
Signed-off-by: Will Deacon <will@kernel.org>