arm64/sysreg: Standardise naming for WFxT defines

The defines for WFxT refer to the feature as WFXT and use SUPPORTED rather
than IMP. In preparation for automatic generation of defines update these
to be more standard. No functional changes.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220704170302.2609529-12-broonie@kernel.org


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