[media] v4l: document new Bayer and monochrome pixel formats

Document all four 10-bit Bayer formats, 10-bit monochrome and a missing
8-bit Bayer formats.

 create mode 100644 Documentation/DocBook/v4l/pixfmt-srggb10.xml
 create mode 100644 Documentation/DocBook/v4l/pixfmt-srggb8.xml
 create mode 100644 Documentation/DocBook/v4l/pixfmt-y10.xml

[mchehab@redhat.com: remove duplicated symbol for V4L2-PIX-FMT-SGRBG10 and added the corresponding entries at media-entities.tmpl]
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>