vc4: Fix assertion about SFU versus texturing.
vc4: Fix assertion about SFU versus texturing.

We're supposed to be checking that nothing else writes r4, which is done
by the TMU result collection signal, not the coordinate setup.

Avoids a regression when QPU instruction scheduling is introduced.

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler