Patches from DES to create three new kernel config options to control

Patches from DES to create three new kernel config options to control
timeouts in the SA driver (timeouts for space, rewind and erase).  Folks
can lengthen the timeouts if their hardware is especially slow, or shorten
them if they want to be notified of errors a little sooner.

Also, get rid of two OD driver options.  The od driver has been made
obsolete by the da driver.

Reviewed by:	ken, gibbs
Submitted by:	Dag-Erling Coidan Smørgrav <des@FreeBSD.ORG>