media: v4l2-core: remove the unused code

Remove the unused v4l2-core code and remove the
related unused code in rtc6226 driver.

CRs-Fixed: 2774873
Change-Id: Ib1b7fd89f735ba67ec2a38e236a2cecaf5540a53
Signed-off-by: himta ram <hram@codeaurora.org>