gallium/vl: Simplify usage of full range matrices

gallium/vl: Simplify usage of full range matrices

When looking at the full range matrices, it becomes obvious that the difference
between the standard matrices and the full range matrices is that the full
range matrices are multiplied by 1.164. Together with offsetting the y value
with -16/255, this will scale and offset RGB with the desired quantities.

However, the standard SMPTE 240M matrix seems to differ a bit since the
U and V coefficients are only multiplied with 1.138 to get the full range
matrix. This would actually alter the color somewhat so I figure that's an
error. The full range matrix is consistent with Nvidia's VDPAU implementation.

We can also incorporate the ybias in the brightness simplifying the
calculation somewhat.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Reviewed-by: Christian König <christian.koenig@amd.com>