drm-tests: add dma_buf mmap test.

Change vgem_fb_test to mmap_test. Now the mmap_test covers both vgem mmap test
and the dma_buf mmap test.
The dma_buf mmap test runs with -d or --use_dma_buf flag. The vgem mmap test
runs with -v or --use_vgem flag.

Here's help print.
$ mmap_test -h
Usage: ./mmap_test [OPTIONS]
 -h, --help
           Print help.
 -d, --use_dma_buf
           Use dma_buf mmap.
 -v, --use_vgem
           Use vgem mmap.

TEST=mmap_test on Pixel 2015
BUG=chromium:356871
CQ-DEPEND=CL:447437

Change-Id: I659ae6d57ca6969ceeb68cb8079703a0e3c26f49
Reviewed-on: https://chromium-review.googlesource.com/339190
Commit-Ready: Dongseong Hwang <dongseong.hwang@intel.com>
Tested-by: Dongseong Hwang <dongseong.hwang@intel.com>
Reviewed-by: Dongseong Hwang <dongseong.hwang@intel.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
2 files changed