arm64/sme: Fix cut'n'paste in ABI document

The ABI for SME is very like that for SVE so bits of the ABI were copied
but not adequately search and replaced, fix that.

Reported-by: Edmund Grimley-Evans <edmund.grimley-evans@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/20240124-arm64-sve-sme-doc-v2-2-fe3964fb3c19@kernel.org


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