nvmem: core: return error code instead of NULL from nvmem_device_get

nvmem_device_get() should return ERR_PTR() on error or valid pointer
on success, but one of the code path seems to return NULL, so fix it.
Reported-by: NNiklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: NSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/core.c

@@ -679,7 +679,7 @@ static struct nvmem_device *nvmem_find(const char *name)
 	d = bus_find_device_by_name(&nvmem_bus_type, NULL, name);
 
 	if (!d)
-		return NULL;
+		return ERR_PTR(-ENOENT);
 
 	return to_nvmem_device(d);
 }