drm/edid: Rename drm_hdmi_avi_infoframe_colorspace to _colorimetry

The drm_hdmi_avi_infoframe_colorspace() function actually sets the
colorimetry and extended_colorimetry fields in the hdmi_avi_infoframe
structure with DRM_MODE_COLORIMETRY_* values.

To make things worse, the hdmi_avi_infoframe structure also has a
colorspace field used to signal whether an RGB or YUV output is being
used.

Let's remove the inconsistency and allow for the colorspace usage by
renaming the function.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>