85xx: Fix the wrong BCSR address of 8569MDS

The BCSR17[7] = 1 will unlock the write protect of FLASH.
The WP# pin only controls the write protect of top/bottom sector,
That is why we can save env, but we can't write the first sector
before the patch.
Signed-off-by: NDave Liu <daveliu@freescale.com>

board/freescale/mpc8569mds/bcsr.c

@@ -27,7 +27,7 @@
 
 void enable_8569mds_flash_write()
 {
-	setbits_8((u8 *)(CONFIG_SYS_BCSR_BASE + 11), BCSR17_FLASH_nWP);
+	setbits_8((u8 *)(CONFIG_SYS_BCSR_BASE + 17), BCSR17_FLASH_nWP);
 }
 
 void disable_8569mds_flash_write()