libcamera: software_isp: Fix CCM multiplication

A colour correction matrix (CCM) is applied like this to an RGB pixel
vector P:

  CCM * P

White balance must be applied before CCM.  If CCM is used, software ISP
makes a combined matrix by multiplying the CCM by a white balance gains
CCM-like matrix (WBG).  The multiplication should be as follows to do it
in the correct order:

  CCM * (WBG * P) = (CCM * WBG) * P

The multiplication order in Lut software ISP algorithm is reversed,
resulting in colour casts.  Let's fix the order.

Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

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