Use actual kernel headers and display-caf paths if defined

Change-Id: I7338867f6eb4d88b33b610a2b2f93280ed6e71bc
QCMetaData: Add key for interlace

key for interlace set in metadata is being used for thumbnail mode.
If the key is set, two ETB are send to the decoder

Change-Id: I1e4e996f46f022916ab5f4f14ff2c111f04717c1
mm-video: venc: Correct a typo in variable name

A kernel variable was to be defined as unsigned long but
it is mistakenly defined as unsigned only, the space is
missing after long. This bug is silent because unsigned
is also a valid data type by itself.
Corresponding to kernel fix, similar correction is done
in userspace code.

Change-Id: Ie58f275149dc9c85553f75e02594113b1a03ddcf
CRs-fixed: 556771