radeonsi: silence a coverity warning

radeonsi: silence a coverity warning

The following Coverity warning

5378     	tmpl.fetch_args = atomic_fetch_args;
5379     	tmpl.emit = atomic_emit;
>>>     CID 1357115:  Uninitialized variables  (UNINIT)
>>>     Using uninitialized value "tmpl". Field "tmpl.intr_name" is uninitialized.
5380     	bld_base->op_actions[TGSI_OPCODE_ATOMUADD] = tmpl;
5381     	bld_base->op_actions[TGSI_OPCODE_ATOMUADD].intr_name = "add";

... is a false positive, but what the hell. This change should "fix" it.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>