arm64: trans_pgd: make trans_pgd_map_page generic

kexec is going to use a different allocator, so make
trans_pgd_map_page to accept allocator as an argument, and also
kexec is going to use a different map protection, so also pass
it via argument.

Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Link: https://lore.kernel.org/r/20210125191923.1060122-5-pasha.tatashin@soleen.com


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