arm64/sme: Restore SME registers on exit from suspend

[ Upstream commit 95338648 ]

The fields in SMCR_EL1 and SMPRI_EL1 reset to an architecturally UNKNOWN
value. Since we do not otherwise manage the traps configured in this
register at runtime we need to reconfigure them after a suspend in case
nothing else was kind enough to preserve them for us.

The vector length will be restored as part of restoring the SME state for
the next SME using task.

Fixes: a1f4ccd2 ("arm64/sme: Provide Kconfig for SME")
Reported-by: Jackson Cooper-Driver <Jackson.Cooper-Driver@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240213-arm64-sme-resume-v3-1-17e05e493471@kernel.org


Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>