[ARM] 3016/1: Replace map_desc.physical with map_desc.pfn

Patch from Deepak Saxena

Convert map_desc.physical to map_desc.pfn. This allows us to add
support for 36-bit addressed physical devices in the static maps
without having to resort to u64 variables.

Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>