pinctrl: bcm283x: Read address from DT in ofdata_to_platdata

pinctrl: bcm283x: Read address from DT in ofdata_to_platdata

Factor out reading IP base address to ofdata_to_platdata function, which
is designed for this purpose. Also, drop the dev->priv NULL check, since
this is already done by the dm core when allocating space using
priv_auto_alloc_size feature. (in drivers/core/device.c ->
device_ofdata_to_platdata).

Cc: Matthias Brugger <mbrugger@suse.com>
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>