msm: ipa: alloc memory using kmalloc instead of dma_alloc_coherent

Atomic dma coherent memory pool is very limited in size so avoid
using that pool for control plane operations which typically
need much less than a page worth of memory.

Change-Id: I84df76697da2a371052481cce30551b7227dae69
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>