msm: Increase the kernel virtual area to include lowmem

Even though lowmem is accounted for in vmalloc space, allocation
comes only from the region bounded by VMALLOC_START and VMALLOC_END.
The kernel virtual area can now allocate from any unmapped region
starting from PAGE_OFFSET.

Change-Id: I291b9eb443d3f7445fd979bd7b09e9241ff22ba3
Signed-off-by: Neeti Desai <neetid@codeaurora.org>