drm/msm: rename kernel module to msm_drm

This change modifies the module name to something that's more
specific to DRM support for msm to minimize the possibility of
name clashes with other msm drivers.

Change-Id: Ie1a933bc994657c868c50e3e00b7a954190e7c41
Signed-off-by: Clarence Ip <cip@codeaurora.org>