target-arm: make RFE usable with any register

The rfe instruction can be used with any register, not just sp. Adjust the
condition check accordingly.
Signed-off-by: NAdam Lackorzynski <adam@os.inf.tu-dresden.de>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

target-arm/translate.c

@@ -6132,7 +6132,7 @@ static void disas_arm_insn(CPUState * env, DisasContext *s)
                 dead_tmp(addr);
             }
             return;
-        } else if ((insn & 0x0e5fffe0) == 0x081d0a00) {
+        } else if ((insn & 0x0e50ffe0) == 0x08100a00) {
             /* rfe */
             int32_t offset;
             if (IS_USER(s))