msm: kgsl: Record the cacheability attribute of ion buffers

Query whether an ion buffer is cached using the dmabuf API
dma_buf_get_flags. Record this information in the memdesc
so that any cache operations requested on the ion buffer
can be honored.

Change-Id: Ie763047260108a8b5b2073b60d7a6e51408ae543
Signed-off-by: Sushmita Susheelendra <ssusheel@codeaurora.org>