etnaviv: fix blend color for RB swapped rendertargets

Same as with the colormasks, the blend color needs to be swizzled according
to the rendertarget format.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Reviewed-by: Wladimir J. van der Laan <laanwj@gmail.com>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
4 files changed