msm: ipa3: fix GSI ring DMA allocation parameters

DMA coherent allocation was done with inappropriate
flags causing memory allocation to fail occasionally.
Use GFP_KERNEL flag as well as fix up some cleanup
actions.

CRs-Fixed: 1060305
Change-Id: I93c9340439dd65c50764dd078071bf66f65a9464
Signed-off-by: Ghanim Fodi <gfodi@codeaurora.org>