onewire: w1-gpio: add ext_pullup_enable pin in platform data

onewire: w1-gpio: add ext_pullup_enable pin in platform data

In the process of porting boards to devicetree implemenation, we should
keep information about external circuitry where they belong - the
individual drivers.

This patch adds a way to specify a GPIO to drive the (optional) external
pull-up logic, rather than using a function pointer for that.

Signed-off-by: Daniel Mack <[email protected]>
Acked-by: Evgeniy Polyakov <[email protected]>
Acked-by: Ville Syrjälä <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>