disas/microblaze: Remove unused REG_PC define

The REG_PC define in disas/microblaze.c clashes with a define in
the Linux SPARC system headers:

/home/pm215/qemu/disas/microblaze.c:162:0: error: "REG_PC" redefined [-Werror]
 #define REG_PC  32 /* PC */

In file included from /usr/include/signal.h:326:0,
                 from /home/pm215/qemu/include/qemu/osdep.h:86,
                 from /home/pm215/qemu/disas/microblaze.c:36:
/usr/include/sparc64-linux-gnu/sys/ucontext.h:96:0: note: this is the location of the previous definition
 #define REG_PC  (1)

Since the code doesn't actually use the REG_PC define
anywhere, the simplest fix is just to remove it.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 1490272961-1128-1-git-send-email-peter.maydell@linaro.org

disas/microblaze.c

@@ -159,7 +159,7 @@ enum microblaze_instr_type {
 #define MIN_PVR_REGNUM 0
 #define MAX_PVR_REGNUM 15
 
-#define REG_PC  32 /* PC */
+/* 32 is REG_PC */
 #define REG_MSR 33 /* machine status reg */
 #define REG_EAR 35 /* Exception reg */
 #define REG_ESR 37 /* Exception reg */