spl:falcon:trats: Fix SPL image size computing.

"spl_imgsize" was set as decimal variable by "setexpr"
and this causes wrong image size written by "ext4write".
Preset this val with "0x" prefix allow to fix this issue.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Minkyu Kang <mk7.kang@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

include/configs/trats.h

@@ -199,6 +199,7 @@
 	"splfile=falcon.bin\0" \
 	"spl_export=" \
 		   "setexpr spl_imgsize ${splsize} + 8 ;" \
+		   "setenv spl_imgsize 0x${spl_imgsize};" \
 		   "setexpr spl_imgaddr ${spladdr} - 8 ;" \
 		   "setexpr spl_addr_tmp ${spladdr} - 4 ;" \
 		   "mw.b ${spl_imgaddr} 0x00 ${spl_imgsize};run loaduimage;" \