msm: kgsl: Fix DMA API warnings

Currently, we call dma_buf_map_attachment() with dma direction
DMA_TO_DEVICE and DMA_FROM_DEVICE while calling
dma_buf_unmap_attachment(). A mismatch of DMA direction during map,
unmap or sync of a buffer triggers a warning when CONFIG_DMA_API_DEBUG
is enabled like the below one:

[6.994847]  WARNING: CPU: 7 PID: 785 at /buildbot/src/partner-android/r-dev-msm-4.14/private/msm-google/lib/dma-debug.c:1153 check_unmap+0x664/0xd3c
[6.994852]  Kernel panic - not syncing: panic_on_warn set ...
[6.994852]
[6.994859]  CPU: 7 PID: 785 Comm: android.hardwar Tainted: G S         O    4.14.117-g3254dd9dae41-ab6213388 #1
[6.994862]  Hardware name: Qualcomm Technologies, Inc.
[6.994866]  Call trace:
[6.994873]   dump_backtrace+0x0/0x1f0
[6.994877]   show_stack+0x14/0x1c
[6.994883]   dump_stack+0xa8/0xe0
[6.994887]   panic+0x1ac/0x3a4
[6.994890]   __stack_chk_fail+0x0/0x18
[6.994893]   report_bug+0x148/0x184
[6.994896]   bug_handler+0x28/0x84
[6.994899]   brk_handler+0x80/0x13c
[6.994902]   do_debug_exception+0xc4/0x14c
[6.994905]   el1_dbg+0x18/0x74
[6.994907]   check_unmap+0x664/0xd3c
[6.994911]   debug_dma_unmap_sg+0x8c/0x160
[6.994916]   ion_unmap_dma_buf+0x1f4/0x270
[6.994920]   dma_buf_unmap_attachment+0x24/0x38
[6.994925]   kgsl_destroy_ion+0xa8/0xd0
[6.994928]   kgsl_mem_entry_destroy+0x8c/0x14c
[6.994932]   kgsl_ioctl_gpuobj_free+0x388/0x420
[6.994936]   kgsl_ioctl_helper+0x118/0x148
[6.994939]   kgsl_ioctl+0x30/0xbc
[6.994942]   do_vfs_ioctl+0x5cc/0x910
[6.994945]   SyS_ioctl+0x88/0x94
[6.994948]   el0_svc_naked+0x34/0x38

We can fix these warnings by using a consistent DMA direction during
map, unmap and sync which is DMA_BIDIRECTIONAL because GPU may read
or write from this buffer.

Change-Id: I3f9c7c27418e5e7d0db44761fa68d27560aa8aaf
Signed-off-by: Akhil P Oommen <akhilpo@codeaurora.org>