arm64: Rename SVE/SME cpu_enable functions

The arm64_cpu_capabilities::cpu_enable() callbacks for SVE, SME, SME2,
and FA64 are named with an unusual "${feature}_kernel_enable" pattern
rather than the much more common "cpu_enable_${feature}". Now that we
only use these as cpu_enable() callbacks, it would be nice to have them
match the usual scheme.

This patch renames the cpu_enable() callbacks to match this scheme. At
the same time, the comment above cpu_enable_sve() is removed for
consistency with the other cpu_enable() callbacks.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>