kselftest/arm64: signal: Add SVE to the set of features we can check for

Allow testcases for SVE signal handling to flag the dependency and be
skipped on systems without SVE support.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210819134245.13935-2-broonie@kernel.org


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