ARM: keystone2: configs: Correct burn_uboot_sp erase size

The NOR flash on Keystone 2 evms has a u-boot-spl partition size of
0x80000.

Currently burn_uboot_spi will erase 0x100000 from the spi NOR which will
cause a partial erase of the misc partition.

Fix this by correcting the erase size.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>

include/configs/ti_armv7_keystone2.h

@@ -249,7 +249,7 @@
 	"get_mon_net=dhcp ${addr_mon} ${tftp_root}/${name_mon}\0"	\
 	"get_mon_ubi=ubifsload ${addr_mon} ${name_mon}\0"		\
 	"get_uboot_net=dhcp ${loadaddr} ${tftp_root}/${name_uboot}\0"	\
-	"burn_uboot_spi=sf probe; sf erase 0 0x100000; "		\
+	"burn_uboot_spi=sf probe; sf erase 0 0x80000; "		\
 		"sf write ${loadaddr} 0 ${filesize}\0"		\
 	"burn_uboot_nand=nand erase 0 0x100000; "			\
 		"nand write ${loadaddr} 0 ${filesize}\0"		\