The better thing to do would be as follows:
* If you manage your own DNS, create a DNS entry for 'aruba-master' with the IP address of your master controller as the A-record. When the AP comes up and pulls an IP address it will do a DNS lookup for 'aruba-master' and find your master IP and connect.
* If you don't manage your own DNS, but manage your DHCP, create a scope with option 43 configured as the IP address of your master controller, and option 60 as 'ArubaAP'. When the AP gets the DHCP response, it will contain the Option43/60 telling the AP where to look. (http://www.arubanetworks.com/techdocs/ArubaOS_60/UserGuide/DHCP_Option_43.php)
* If you do NONE of that, you CAN statically set the master-ip and provision it on to the AP directly. Note though that if the master IP ever changes, that AP will be orphaned until it is re-provisioned. It will still pull and IP address just fine, unless you disable DHCP and statically set an IP address on the AP (NOT recommended).