gpio: No NULL owner

Sometimes a GPIO is fetched with NULL as parent device, and
that is just fine. So under these circumstances, avoid using
dev_name() to provide a name for the GPIO line.

Change-Id: Iacf2ef35d50118cd755e26ed4211c3c4b1289ff2
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Git-commit: 7d18f0a14aa6a0d6bad39111c1fb655f07f71d59
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Srinivasarao P <spathi@codeaurora.org>