loader: issue edd probe before legacy ah=08 and detect no media

while probing for drives, use int13 extended info before standard one and
provide workaround for case we are not getting needed information in case
of floppy drive.

In case of INT13 errors, there are (at least) 3 error codes appearing in case
of missin media - 20h, 31h and 80h. Flag the no media and do not print an
error.

Differential Revision: https://reviews.freebsd.org/D17667