[POWERPC] 86xx: mpc8610_hpcd: fix second serial port

DIU platform code should not just write to the PIXIS' BRDCFG0 register,
it should set and clear its own bits only, otherwise it will break
firmware setup (in fact it breaks second uart).

Also get rid of magic numbers in the related code.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/platforms/86xx/mpc8610_hpcd.c

@@ -217,11 +217,21 @@ void mpc8610hpcd_set_gamma_table(int monitor_port, char *gamma_table_base)
 	}
 }
 
+#define PX_BRDCFG0_DVISEL	(1 << 3)
+#define PX_BRDCFG0_DLINK	(1 << 4)
+#define PX_BRDCFG0_DIU_MASK	(PX_BRDCFG0_DVISEL | PX_BRDCFG0_DLINK)
+
 void mpc8610hpcd_set_monitor_port(int monitor_port)
 {
-	static const u8 bdcfg[] = {0xBD, 0xB5, 0xA5};
+	static const u8 bdcfg[] = {
+		PX_BRDCFG0_DVISEL | PX_BRDCFG0_DLINK,
+		PX_BRDCFG0_DLINK,
+		0,
+	};
+
 	if (monitor_port < 3)
-		*pixis_bdcfg0 = bdcfg[monitor_port];
+		clrsetbits_8(pixis_bdcfg0, PX_BRDCFG0_DIU_MASK,
+			     bdcfg[monitor_port]);
 }
 
 void mpc8610hpcd_set_pixel_clock(unsigned int pixclock)