msm: move event_timer header to machine independent location

Move event_timer header to a machine independent location in
kernel. Change the source files which are referring to this
header and point them to a new header location.

Change-Id: I52a6624c29a3d959c87570497a90a56649f93ab9
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>