Fix resizing of /rw partition (private.img)

Offline resize requires to run fsck -f first. Because we support only
growing that image, we can simply use online resize instead.

This finally fixes qubesos/qubes-issues#772

vm-init.d/qubes-core

@@ -60,8 +60,8 @@ start()
 			mkfs.ext4 -m 0 -q /dev/xvdb || exit 1
 		fi
 
-		resize2fs /dev/xvdb 2> /dev/null || echo "'resize2fs /dev/xvdb' failed"
 		mount /rw
+		resize2fs /dev/xvdb 2> /dev/null || echo "'resize2fs /dev/xvdb' failed"
 
         if ! [ -d /rw/home ] ; then
             echo

vm-systemd/mount-home.sh

@@ -8,9 +8,9 @@ if dd if=/dev/zero bs=512 count=$private_size_512 | diff /dev/xvdb - >/dev/null;
     mkfs.ext4 -m 0 -q /dev/xvdb || exit 1
 fi
 
-resize2fs /dev/xvdb 2> /dev/null || echo "'resize2fs /dev/xvdb' failed"
 tune2fs -m 0 /dev/xvdb
 mount /rw
+resize2fs /dev/xvdb 2> /dev/null || echo "'resize2fs /dev/xvdb' failed"
 
 if ! [ -d /rw/home ] ; then
     echo