reset: remove redundant null check on pointer dev

Pointer dev is being dereferenced when passed to the inlined
functon dev_name, however, dev is later being null checked
so at first this seems like a potential null pointer dereference.

In fact, _reset_control_get_from_lookup is only ever called from
__reset_control_get, right after checking dev->of_node hence
dev can never be null.  Clean this up by removing the redundant
null check.

Thanks to Philipp Zabel for spotting that dev can never be null.

Addresses-Coverity: ("Dereference before null check")
Fixes: 6691dffa ("reset: add support for non-DT systems")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>