ARM: 8396/1: use phys_addr_t in pfn_to_kaddr()

This patch fixes pfn_to_kaddr() to use phys_addr_t.  Without this,
this macro is broken on LPAE systems. For physical addresses above
first 4GB result of shifting pfn with PAGE_SHIFT may be truncated.

Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>