powerpc: fix warning when compiling immap_qe.h

Fix the warnings genereted by arch/powerpc/include/asm/immap_qe.h when
CONFIG_PHYS_ADDR_T_64BIT is defined:

immap_qe.h: In function 'immrbar_virt_to_phys':
immap_qe.h:472:8: warning: cast from pointer to integer of different size
immap_qe.h:472:24: warning: cast from pointer to integer of different size
immap_qe.h:473:5: warning: cast from pointer to integer of different size
immap_qe.h:473:21: warning: cast from pointer to integer of different size
immap_qe.h:474:36: warning: cast from pointer to integer of different size

Note that the QE does not support 36-bit physical addresses, so even when
CONFIG_PHYS_ADDR_T_64BIT is defined, the QE MURAM must be located below the
4GB boundary.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>