arm64/sve: Rename find_supported_vector_length()

The function has SVE specific checks in it and it will be more trouble
to add conditional code for SME than it is to simply rename it to be SVE
specific.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20211019172247.3045838-6-broonie@kernel.org


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