arm64/sme: Fix SVE/SME typo in ABI documentation

Fix a cut'n'paste error.

Reported-by: Luis Machado <luis.machado@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220608115915.251870-1-broonie@kernel.org


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>