msm: ipa: use smem_alloc2 to allocate SMEM pipe mem

smem_alloc used previously assumes modem will alloc the
item before IPA driver is initialized. smem_alloc2 will
alloc the item if not already allocated.

Change-Id: I4bd1e8d85a325180e58507b300984db882d8e18d
Signed-off-by: Ravi Gummadidala <rgummadi@codeaurora.org>