pata_bf54x: handle portmuxing of pins through GPIO PORTs

By default, the PATA pins are routed to the async address lines in which
case, no peripheral muxing needs to be done.  However, if the pins get
routed through the GPIO PORTs pins, we need to make sure to request them
so that the muxing is properly set up.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>