85xx/p1_p2_rdb: not able to modify "$bootfile" environment variable

Because the variable was getting defined twice.
Signed-off-by: NPoonam Aggrwal <poonam.aggrwal@freescale.com>
Acked-by: NAndy Fleming <afleming@freescale.com>

include/configs/P1_P2_RDB.h

@@ -568,7 +568,6 @@ extern unsigned long get_board_sys_clk(unsigned long dummy);
 	"netdev=eth0\0"						\
 	"uboot=" MK_STR(CONFIG_UBOOTPATH) "\0"				\
 	"loadaddr=1000000\0"			\
-	"bootfile=uImage\0"	\
 	"tftpflash=tftpboot $loadaddr $uboot; "			\
 		"protect off " MK_STR(TEXT_BASE) " +$filesize; "	\
 		"erase " MK_STR(TEXT_BASE) " +$filesize; "		\