mkimage: make images a little bigger by default

new rpi kernels are a bit bigger, apparently

Author: classabbyamp

mkimage.sh

@@ -65,7 +65,7 @@ usage() {
 	 -b <fstype>    /boot filesystem type (default: vfat)
 	 -B <bsize>     /boot filesystem size (default: 256MiB)
 	 -r <fstype>    / filesystem type (default: ext4)
-	 -s <totalsize> Total image size (default: 768MiB)
+	 -s <totalsize> Total image size (default: 900MiB)
 	 -o <output>    Image filename (default: guessed automatically)
 	 -x <num>       Number of threads to use for image compression (default: dynamic)
 	 -h             Show this help and exit
@@ -131,7 +131,7 @@ esac
 # formated FAT16, and an approximately 512MiB root partition formatted
 # ext4.  More exotic combinations are of course possible, but this
 # combination works on all known platforms.
-: "${IMGSIZE:=768M}"
+: "${IMGSIZE:=900M}"
 : "${BOOT_FSTYPE:=vfat}"
 : "${BOOT_FSSIZE:=256MiB}"
 : "${ROOT_FSTYPE:=ext4}"