mpc8569mds: fix CONFIG_ENV_SIZE

CONFIG_ENV_SIZE of MPC8569MDS was wrongly set to CONFIG_ENV_SECT_SIZE which
is 128KB, so it took longer time to do crc32 calculation for ENV than it should
do. It causes the bootup for MPC8569MDS significantly slow. This patch fixs it
to 0x2000(8KB), also fix the comment for CONFIG_ENV_SECT_SIZE to correct size.

Signed-off-by: Kai.Jiang <Kai.Jiang@freescale.com
Signed-off-by: NHaiying Wang <Haiying.Wang@freescale.com>
Signed-off-by: NKumar Gala <galak@kernel.crashing.org>

include/configs/MPC8569MDS.h

@@ -505,8 +505,8 @@ extern unsigned long get_clock_freq(void);
 #else
 #define CONFIG_ENV_IS_IN_FLASH	1
 #define CONFIG_ENV_ADDR		(CONFIG_SYS_MONITOR_BASE - CONFIG_ENV_SECT_SIZE)
-#define CONFIG_ENV_SECT_SIZE	0x20000	/* 256K(one sector) for env */
-#define CONFIG_ENV_SIZE		CONFIG_ENV_SECT_SIZE
+#define CONFIG_ENV_SECT_SIZE	0x20000	/* 128K(one sector) for env */
+#define CONFIG_ENV_SIZE		0x2000
 #endif
 
 #define CONFIG_LOADS_ECHO	1	/* echo on for serial download */