target/mips: Remove identical if/else branches

Remove the segment:

      if (other_tc == other->current_tc) {
          tccause = other->CP0_Cause;
      } else {
          tccause = other->CP0_Cause;
      }

Original contributor can't remember what was his intention.

Fixes: 5a25ce9 ("mips: Hook in more reg accesses via mttr/mftr")
Buglink: https://bugs.launchpad.net/qemu/+bug/1885718
Signed-off-by: Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>
Message-Id: <20200701182559.28841-2-aleksandar.qemu.devel@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

target/mips/cp0_helper.c

@@ -375,16 +375,9 @@ target_ulong helper_mftc0_entryhi(CPUMIPSState *env)
 target_ulong helper_mftc0_cause(CPUMIPSState *env)
 {
     int other_tc = env->CP0_VPEControl & (0xff << CP0VPECo_TargTC);
-    int32_t tccause;
     CPUMIPSState *other = mips_cpu_map_tc(env, &other_tc);
 
-    if (other_tc == other->current_tc) {
-        tccause = other->CP0_Cause;
-    } else {
-        tccause = other->CP0_Cause;
-    }
-
-    return tccause;
+    return other->CP0_Cause;
 }
 
 target_ulong helper_mftc0_status(CPUMIPSState *env)