msm: pm-boot: Use different memory API to allocate block of memory

Currently PM driver uses the memory given by the "memblock_alloc"
api. These initial memory bytes are programmed with warm boot entry
sequences to come out of the low power modes. Currently this API is
causing the system instability with 1GB DDR parts and HIGH MEM is
enabled. To resolve this issue use a different API to allocate the
memory i.e memblock_remove.

Change-Id: I1016d63f1154e7b4d4d4b702202878d6f93cecf0
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>