r600/pipe: Stop leaking context->start_compute_cs_cmd.buf on EG/CM
r600/pipe: Stop leaking context->start_compute_cs_cmd.buf on EG/CM

Found while tracking down memory leaks in VDPAU playback

Reviewed-by: Tom Stellard <thomas.stellard@amd.com>

CC: "10.0" <59f39c0db42d4479a46b02d4d2bc11120e37bb44@lists.freedesktop.org>

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