msm: ipa3: Use proper allocation flag in case of shutdown

In case of device shutdown DMA memory allocation might
fail with GFP_KERNEL flag. This failure might occur
since the calling process received SIGKILL.In order to
avoid that scenario perform the DMA allocation with atomic
flag.

CRs-Fixed: 1116368
Signed-off-by: Amir Levy <alevy@codeaurora.org>
Change-Id: Id4d29d0f4a25f5630911db79c236fb08da752be4