Migrate demux driver from kernel 3.10 to 3.18

This change migrates all the relevant files and updates made
to the dvb/demux framework, required for mpq demux driver.
The snapshot is taken as of msm-3.10, commit 1d1c751febc370 ("Merge "msm:
kgsl: Set IOMMU context and AHB offsets for A5xx"")
In addition, introduce a few code changes to reduce checkpatch warnings,
typos and other style issues.

Change-Id: I5eee6818ff81178470677e981179f029a08a58ef
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>