Revert "staging: gasket: core: hold reference to pci_dev while used"

There's no need to take an additional reference on the pci_dev structure
for the pointer copy saved in gasket data structures.

This reverts commit:
8dd8a48b ("staging: gasket: core: hold reference to pci_dev while used")

Reported-by: Dmitry Torokhov <dtor@chromium.org>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>