msm: kgsl: Use phys_addr_t to store the ptbase

We compute the ptbase from the SMMU driver and read the TTBR0 to
compare the two. However, the ptbase obtained from the SMMU driver
is a phys_addr_t and the one we read from TTBR0 is an unsigned int.
Change it to a phys_addr_t to avoid comparison errors.

Change-Id: I46c249ab98eb7ad6d4a15388267a84f1210111ff
Signed-off-by: Shrenuj Bansal <shrenujb@codeaurora.org>