configs/aspeed_ast2500evb: increase kernel partition size

Linux images are growing larger, and the current kernel partition size
of 4352K is no longer sufficient. Increase the partition size to
accommodate the larger images.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Julien Olivain <ju.o@free.fr>

board/aspeed/ast2500-evb/genimage.cfg

@@ -30,11 +30,11 @@ image flash.img {
 	partition fitimage {
 		image = "image.itb"
 		offset = 512K
-		size = 4352K
+		size = 6000K
 	}
 
 	partition spare {
-		offset = 4864K
-		size = 27904K
+		offset = 6512K
+		size =  26256K
 	}
 }