The clock gate used by orion_nand is not available on all platforms.
When getting this optional clock gate, the code masked all errors.
Let's be more precise here and actually only allow ENOENT.

EPROBE_DEFER is handled like any other error code since probe deferral
is not supported by drivers using module_platform_driver_probe().
Signed-off-by: NSimon Baatz <gmbnomis@gmail.com>
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>