msm: pil: Use phys_addr_t for physical address

Update the physical address type to be phys_addr_t for the
following reasons:

1) Match with the return type of the pil_get_entry_addr()
2) If the image is placed above 4GB e.g. LPAE supported case,
   phys_addr_t can hold physical address.

Change-Id: Ifcffc336b7b94a6f864afc05c3f5a3ffdc813231
Signed-off-by: Tianyi Gou <tgou@codeaurora.org>