arm64: io: Rename ioremap_prot() to __ioremap_prot()

arm64: io: Rename ioremap_prot() to __ioremap_prot()

Rename our ioremap_prot() implementation to __ioremap_prot() and convert
all arch-internal callers over to the new function.

ioremap_prot() remains as a #define to __ioremap_prot() for
generic_access_phys() and will be subsequently extended to handle user
permissions in 'prot'.

Cc: Zeng Heng <zengheng4@huawei.com>
Cc: Jinjiang Tu <tujinjiang@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>