arm64: add early_ioremap support

arm64: add early_ioremap support

Add support for early IO or memory mappings which are needed before the
normal ioremap() is usable.  This also adds fixmap support for permanent
fixed mappings such as that used by the earlyprintk device register
region.

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit bf4b558eba920a38f91beb5ee62a8ce2628c92f7)
Signed-off-by: Mark Brown <broonie@linaro.org>
Conflicts:
	arch/arm64/Kconfig
	arch/arm64/mm/ioremap.c