microblaze: Fix -Os right shift optimization is allowed into delay slot

During picolibc testing, it's found that `-Os` produces assembly code that
compiler squeezes into a single delay slot. Thus, only the first
instruction (the one in delay slot) emitted by this optimization is
executed and the rest is skipped.

This is a regression introduced by applying Microblaze gcc patches.

Signed-off-by: Alp Sayin <alpsayin@gmail.com>

Author: alpsayin

gcc/config/microblaze/microblaze.md

@@ -2286,7 +2286,7 @@ else
     output_asm_insn ("bneid\t%3,.-4", operands);
     return "sra\t%0,%0";
   }
-  [(set_attr "type"    "arith")
+  [(set_attr "type"    "multi")
   (set_attr "mode"    "SI")
   (set_attr "length"  "20")]
 )