msm: vidc: Add support to read venus version through debugfs

Currently Venus release version is printed in kernel logs. So
to get venus version user needs to run video playback\encoding
everytime. Storing version in debugfs is handy.

Change-Id: I6d93c374a4402d41f3912b71f20fb68305d9d742
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>