w1: ds2490 fix and enable hardware search

The hardware search was failing without the COMM_RST flag.  Enabled
the flag and rewrote the function to handle more than one buffer of
results and to continuing where the search left off.  Remove hardware
search note from the limitations now that it works.  The "w1: ds2490
USB setup fixes" change went from 23.16 seconds to about 3 seconds,
this takes the time for the search down to .307346 seconds.

Signed-off-by: David Fries <David@Fries.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>