merge_config.sh: Display usage if given too few arguments

Two or more arguments are always expected. Show usage and exit if
given less.

Change-Id: I1e503495f34eab3f181238a1aa877a4aee3b7e5e
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
1 file changed