into separate xxx_ioctl() functions.
* place KASSERT(req != PRU_CONTROL) inside xxx_userreq() as it is now
inappropriate for req = PRU_CONTROL in xxx_userreq().
* replace calls to pr_generic() with req = PRU_CONTROL with pr_ioctl().
* remove & fixup references to PRU_CONTROL xxx_userreq() function comments.
* fix various comments references for xxx_userreq() that mentioned
PRU_CONTROL as xxx_userreq() no longer handles the request.
a further change will follow to fix parameter and naming inconsistencies
retained from original code.
Reviewed by rmind@