intel/brw: Remove special treatment for 2-src in emit() helper

For Gfx9+ no 2-src instructions need sources to fixed up.  Special
treatment remains for 3-src instructions.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30911>

src/intel/compiler/brw_fs_builder.h

@@ -315,9 +315,7 @@ namespace brw {
          /* Use the emit() methods for specific operand counts to ensure that
           * opcode-specific operand fixups occur.
           */
-         if (n == 2) {
-            return emit(opcode, dst, srcs[0], srcs[1]);
-         } else if (n == 3) {
+         if (n == 3) {
             return emit(opcode, dst, srcs[0], srcs[1], srcs[2]);
          } else {
             return emit(fs_inst(opcode, dispatch_width(), dst, srcs, n));