syscon: Do not return NULL when driver is not selected
Both syscon_base_lookup_by_pdevname() and
syscon_base_lookup_by_phandle(), when implemented, do not return NULL,
so none of the code using those function is written to check for that.
Change returns to ERR_PTR(-ENOSYS), to avoid having that problem.
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>