Set HAL path to media-caf-kk_2.7

Set media variant to caf-kk_2.7 to build this HAL.
mm-video: Add NO_IOMMU flag and enable it by default for msm8660

Change-Id: Ibb76e4dead9db55619dc7fc64bfd17fa96208dc9
media-caf: Avoid collision with FFMPEG plugin

Change-Id: Ica2cdf9f6572ec18f396d25758cbb2be1359ac0b