ahci: attachment to atapi device

[Matthew Dillon]

    I add yet another kenv for you to try. 

    set hint.ahci.nofeatures	in /boot/loader.conf or on the boot loader
				command line.

    I also enhanced the output to indicate which setup command was generating
    the CMD TIMEOUT.  It should say just after the CMD TIMEOUT stuff.

    e.g.

    CMD TIMEOUT ...
	....
	...
	...
	STS=...
    ahcix.x: Unable to set BLAHBLAH

    I'd like to know which setup command it was failing on, if it was
    failing on one, and whether setting hint.ahci.nofeatures fixes the
    problem.

						-Matt