nv50/ir: fix srcMask computation for TG4 and TXF
This affects which inputs are marked as used. In a situation where only
the texture instruction uses an input, it might have been ignored as
unused due to input masks.
Affects subtests of KHR-GL45.texture_cube_map_array.sampling
Signed-off-by:
Ilia Mirkin <imirkin@alum.mit.edu>
Cc: mesa-stable@lists.freedesktop.org