i965/vec4: Stop pretending to support indirect output stores

i965/vec4: Stop pretending to support indirect output stores

Since we're using nir_lower_outputs_to_temporaries to shadow all our
outputs, it's impossible to actually get an indirect store.  The code we
had to "handle" this was pretty bogus as it created a register with a
reladdr and then stuffed it in a fixed varying slot without so much as a
MOV.  Not only does this not do the MOV, it also puts the indirect on the
wrong side of the transaction.  Let's just delete the broken dead code.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>