v4l2src: fix RGB32 colorspace deinitions
v4l2src: fix RGB32 colorspace deinitions

This patch makes RGB32 colorspace definitions used in the caps negotiation
suitable for actual v4l2 driver's output format.

matsu/gst-plugins-good,matsu/gst-plugins-good,matsu/gst-plugins-good,matsu/gst-plugins-good