msm: 8960: Add correct PASR mask support

The current system does not use the correct PASR masks for turning
off sections of memory. It will also crash if the SPARSEMEM section_size
is changed to smaller values.

This fix calculates the correct masks and removes the dependency on
the SPARSEMEM section_size. It will accurately calculate the mask
regardless of memory size and configuration.

MAX_NR_REGIONS has been increased to 32 to account for the largest
system containing four memory banks, each divided into 8 sections.

Change-Id: Idaf05a06c1430e6d353fddafa305b57e400dfb8c
CRs-fixed: 329575
Signed-off-by: Jack Cheung <jackc@codeaurora.org>