Migrate demux driver from kernel 3.18 to 4.4

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-3.18,
'commit e12c33f73fb0 ("Merge defconfig: Enabling confg INET_DIAG_DESTROY")'

In addition, introduce a few code changes to reduce checkpatch
warnings, typos and other style issues.

CRs-Fixed: 1057562
Change-Id: Ia50bd897f6bf4c0ea7adc27d53a657090a09e229
Signed-off-by: Udaya Mallavarapu <udaym@codeaurora.org>