S390: modify the TB opcode name

https://crrev.com/c/3222763 has added a new global value `TB`
which is the same as our `test block` opcode. Cl is adding an
underscore to resolve the naming issue.

Change-Id: I4744f14dd594d4a58ed14d7651a6b7a0cad62ba8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3226801Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#77413}

src/codegen/s390/constants-s390.h

@@ -1203,7 +1203,7 @@ using SixByteInstr = uint64_t;
   V(pt, PT, 0xB228)       /* type = RRE   PROGRAM TRANSFER  */                 \
   V(iske, ISKE, 0xB229)   /* type = RRE   INSERT STORAGE KEY EXTENDED  */      \
   V(rrbe, RRBE, 0xB22A)   /* type = RRE   RESET REFERENCE BIT EXTENDED  */     \
-  V(tb, TB, 0xB22C)       /* type = RRE   TEST BLOCK  */                       \
+  V(tb, TB_, 0xB22C)      /* type = RRE   TEST BLOCK  */                       \
   V(dxr, DXR, 0xB22D)     /* type = RRE   DIVIDE (extended HFP)  */            \
   V(pgin, PGIN, 0xB22E)   /* type = RRE   PAGE IN  */                          \
   V(pgout, PGOUT, 0xB22F) /* type = RRE   PAGE OUT  */                         \