target/xtensa: fix pasto in pfwait.r opcode name

Core xtensa opcode table has pfwait.o instead of pfwait.r. Fix that.

Fixes: c884400f2988 ("target/xtensa: implement block prefetch option opcodes")
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
diff --git a/target/xtensa/translate.c b/target/xtensa/translate.c
index 37f65b1..1010c1c 100644
--- a/target/xtensa/translate.c
+++ b/target/xtensa/translate.c
@@ -3746,7 +3746,7 @@
         .name = "pfwait.a",
         .translate = translate_nop,
     }, {
-        .name = "pfwait.o",
+        .name = "pfwait.r",
         .translate = translate_nop,
     }, {
         .name = "pitlb",