i2c: core: Allow whole core to use i2c_dev_irq_from_resources

Remove the static from i2c_dev_irq_from _resources so that other parts
of the core code can use this helper function.

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>