action: fix move argument parsing

At one point in time it was anticipated that the move action
might take multiple arguments.  So it used the multi argument
setting of "-2"...

But the current implementation expects one argument only.  But
the -2 setting allows zero arguments which isn't expected.  So
enforce 1 argument.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
1 file changed