msm: mdss: dsi: add support for 64-bit arch

Initial work for porting msm display drivers
to the 64-bit arch. Modify qualifiers in prints and ensure
pointer casts are done in an appropriate manner for 64-bit.

Signed-off-by: Manoj Rao <manojraj@codeaurora.org>
Change-Id: I0e545d6de0cade2b03599ef197e980d79506f83f