MIPS: alchemy: db1000: use nodes attached to GPIO chips in properties

MIPS: alchemy: db1000: use nodes attached to GPIO chips in properties

GPIO subsystem is switching the way it locates GPIO chip instances for
GPIO references in software nodes by doing identity matching instead of
matching on node names. Switch to using software nodes attached to gpio
chips instead of using freestanding software nodes.

Also stop supplying platform data for the spi-gpio controller since
spi-gpio driver can derive number of chipselect lines from device
properties.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Tested-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>