arm64/sysreg: Remove defines for RPRES enumeration

We have defines for the RPRES enumeration in ID_AA64ISAR2 which do not
follow our normal conventions. Since these defines are never used just
remove them. No functional changes.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220704170302.2609529-15-broonie@kernel.org


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