arm64/cache: Restrict which headers are included in __ASSEMBLY__

arm64/cache: Restrict which headers are included in __ASSEMBLY__

Future changes to generate register definitions automatically will cause
this header to be included in a linker script. This will mean that headers
it in turn includes that are not safe for use in such a context (eg, due
to the use of assembler macros) cause build problems. Avoid these issues by
moving the affected includes and associated defines to the section of the
file already guarded by ifndef __ASSEMBLY__.

Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20220704170302.2609529-6-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>