video: backlight/progear, fix pci device refcounting

Stanse found an ommitted pci_dev_puts on error path in progearbl_probe.
pmu_dev and sb_dev are gotten, but never put when
backlight_device_register fails.

So unify fail paths and put the devs when the failure occurs.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>