vc4: Set unused raddr fields to QPU_R_NOP.
vc4: Set unused raddr fields to QPU_R_NOP.

The simulator assertion fails if you have a write to a reg and then a read
(for example, in the NOP side of an instruction), even if the read isn't
used for anything.  By setting unused raddrs to NOP, we avoid the problem
(since only the phsyical registers are tracked).

metora/MesaGLSLCompiler,jbarczak/glsl-optimizer,dellis1972/glsl-optimizer,tokyovigilante/glsl-optimizer,wolf96/glsl-optimizer,zz85/glsl-optimizer,dellis1972/glsl-optimizer,dellis1972/glsl-optimizer,bkaradzic/glsl-optimizer,zz85/glsl-optimizer,dellis1972/glsl-optimizer,jbarczak/glsl-optimizer,wolf96/glsl-optimizer,wolf96/glsl-optimizer,benaadams/glsl-optimizer,bkaradzic/glsl-optimizer,mcanthony/glsl-optimizer,dellis1972/glsl-optimizer,djreep81/glsl-optimizer,mcanthony/glsl-optimizer,jbarczak/glsl-optimizer,zeux/glsl-optimizer,mcanthony/glsl-optimizer,jbarczak/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,benaadams/glsl-optimizer,zeux/glsl-optimizer,tokyovigilante/glsl-optimizer,benaadams/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,zeux/glsl-optimizer,metora/MesaGLSLCompiler,zeux/glsl-optimizer,tokyovigilante/glsl-optimizer,benaadams/glsl-optimizer,bkaradzic/glsl-optimizer,metora/MesaGLSLCompiler,wolf96/glsl-optimizer,zz85/glsl-optimizer,mcanthony/glsl-optimizer,benaadams/glsl-optimizer,tokyovigilante/glsl-optimizer,jbarczak/glsl-optimizer,wolf96/glsl-optimizer,zeux/glsl-optimizer,tokyovigilante/glsl-optimizer,djreep81/glsl-optimizer,bkaradzic/glsl-optimizer,benaadams/glsl-optimizer,zz85/glsl-optimizer,mcanthony/glsl-optimizer,bkaradzic/glsl-optimizer,djreep81/glsl-optimizer