pinctrl: cherryview: Utilize temporary variable to hold device pointer

By one of the previous clean up change we got a temporary variable to hold
a device pointer. It can be utilized in other calls in the ->probe() and
save a bit of LOCs.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>