OPAL_PRD_MSG call
-------------

The OPAL_PRD_MSG call is used to pass a struct opal_prd_msg from the HBRT
code into opal, and is paired with the OPAL_PRD_MSG message type.

Parameters:
	struct opal_msg *msg

Passes an opal_msg, of type OPAL_PRD_MSG, from the OS to OPAL.