arm64/sve: Split _sve_flush macro into separate Z and predicate flushes

Trivial refactoring to support further work, no change to generated code.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210512151131.27877-2-broonie@kernel.org


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