media: imx: utils: Rename format lookup and enumeration functions

media: imx: utils: Rename format lookup and enumeration functions

Rename the format lookup and enumeration functions according to their
usage:

- Rename imx_media_(find|enum)_format() to *_pixel_format() to
  explicitly state on what formats the functions operate. This aligns
  the naming scheme with the media bus and IPU format functions that
  already end with *_mbus_format() and *_ipu_formats().

- Rename all enumeration functions to pluralize 'formats' at the end, as
  they enumerate multiple formats.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>