boundary: bootscripts: upgrade: fix block count of filesize

The comparison between the new and old U-boot is still done using
$filesize and therefore is correct.

Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>

board/boundary/bootscripts/upgrade.txt

@@ -44,8 +44,10 @@ else
 fi
 
 # Compute block count for filesize and offset
-setexpr cntfile ${filesize} / ${block_size}
 setexpr cntoffset ${offset} / ${block_size}
+setexpr cntfile ${filesize} / ${block_size}
+# Add 1 in case the $filesize is not a multiple of $block_size
+setexpr cntfile ${cntfile} + 1
 
 # Select media partition (if different from main partition)
 mmc dev ${env_dev} ${env_part}