arm64/sysreg: Add hwcap for SVE EBF16

arm64/sysreg: Add hwcap for SVE EBF16

SVE has a separate identification register indicating support for BFloat16
operations. Add a hwcap identifying support for EBF16 in this register,
mirroring what we did for the non-SVE case.

While there is currently an architectural requirement for BF16 support to
be the same in SVE and non-SVE contexts there are separate identification
registers this separate hwcap helps avoid issues if that requirement were
to be relaxed in the future, we have already chosen to have a separate
capability for base BF16 support.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220829154815.832347-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>