target/ppc: Rename TBL to TB on 64-bit

From the earliest PowerPC ISA, TBR (later SPR) 268 has been called TB
and accessed with mftb instruction. The problem is that TB is the name
of the 64-bit register, and 32-bit implementations can only read the
lower half with one instruction, so 268 has also been called TBL and
it does only read TBL on 32-bit.

Change SPR 268 to be called TB on 64-bit implementations.

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

target/ppc/helper_regs.c

@@ -460,7 +460,11 @@ void register_generic_sprs(PowerPCCPU *cpu)
     }
 
     /* Time base */
+#if defined(TARGET_PPC64)
+    spr_register(env, SPR_VTBL,  "TB",
+#else
     spr_register(env, SPR_VTBL,  "TBL",
+#endif
                  &spr_read_tbl, SPR_NOACCESS,
                  &spr_read_tbl, SPR_NOACCESS,
                  0x00000000);

target/ppc/ppc-qmp-cmds.c

@@ -103,7 +103,11 @@ const MonitorDef monitor_defs[] = {
     { "xer", 0, &monitor_get_xer },
     { "msr", offsetof(CPUPPCState, msr) },
     { "tbu", 0, &monitor_get_tbu, },
+#if defined(TARGET_PPC64)
+    { "tb", 0, &monitor_get_tbl, },
+#else
     { "tbl", 0, &monitor_get_tbl, },
+#endif
     { NULL },
 };