arm64: mte: Restore the GCR_EL1 register after a suspend

The CPU resume/suspend routines only take care of the common system
registers. Restore GCR_EL1 in addition via the __cpu_suspend_exit()
function.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>