msm: use dma_alloc_coherent for L1/L2 cache dump buffers

Currently buffers for L1 and L2 cache dump are allocated using
allocate_contiguous_ebi_nomap() api. On devices with more than
2GB of memory, debug image crashes since these buffers end up
being allocated above 2GB address space which the debug image
currently does not support.Hence, use the dma api so as to
have these buffers be allocated below 2GB address space.

CRs-Fixed: 515701
Change-Id: Iaf862753e63fd9f42256c820b3e3ba08b6894bf3
Signed-off-by: Pushkar Joshi <pushkarj@codeaurora.org>