Move from dma_buf_kmap to dma_buf_vmap for ION

Support for dma_buf_kmap() in ION on msm-5.4 will
be removed soon. It will support dma_buf_vmap() in
lieu of dma_buf_kmap(). Making changes for the same
in qseecom driver.

Change-Id: I4c2d6aaef58b41975279a01181c99cdeb18fb769
Signed-off-by: Anmolpreet Kaur <anmolpre@codeaurora.org>