reset: fix non GPIO reset ...

The reset controller structure is zero initialized in the OF
reset case, but as 0 is also a valid GPIO number the current
code tries to assert/deassert the GPIO instead of calling into
the reset controller device.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

reset: Add gpio reset support ...

If a device has the reset-gpios property we can support this through
the reset controller API, so drivers do not have to open code the
support for this property each time themselves as done a few dozen times
in the kernel.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

reset: Allow dummy reset lines ...

Treat NULL as a dummy reset line which is returned by the reset core
when there is no reset line connected to a device (that is, no
reset is described in the device tree). With this consumers can
just use the reset functions without having to check for existence.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

reset: add reset controller framework ...

Add stripped sown version of the reset controller
framework from the Linux kernel.

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>