ypbind-mt: set path of ypdomainname in ypbind script

The script ypbind will cause error if using ypdomainname command
provided by busybox. So add RDEPENDCY on yp-tools and change
the path of ypdomainname.

Signed-off-by: Jian Liu <jian.liu@windriver.com>
Signed-off-by: Wenzong Fan <wenzong.fan@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>