reset: fix optional reset_control_get stubs to return NULL
When RESET_CONTROLLER is not enabled, the optional reset_control_get
stubs should now also return NULL.
Since it is now valid for reset_control_assert/deassert/reset/status/put
to be called unconditionally, with NULL as an argument for optional
resets, the stubs are not allowed to warn anymore.
Fixes: bb475230b8e5 ("reset: make optional functions really optional") Reported-by: Andrzej Hajda <a.hajda@samsung.com> Tested-by: Andrzej Hajda <a.hajda@samsung.com> Reviewed-by: Andrzej Hajda <a.hajda@samsung.com> Cc: Ramiro Oliveira <Ramiro.Oliveira@synopsys.com> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>