glsl: Add missing type inference for ir_binop_bfm.

Matt noticed that this was missing.  Nothing uses this currently.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Paul Berry <stereotype441@gmail.com>

src/glsl/ir.cpp

@@ -400,6 +400,7 @@ ir_expression::ir_expression(int op, ir_rvalue *op0, ir_rvalue *op1)
 
    case ir_binop_lshift:
    case ir_binop_rshift:
+   case ir_binop_bfm:
       this->type = op0->type;
       break;