i2c: ismt: improve usage of devres API

pcim_release() will release any requested region. There is no need to duplicate
this effort in the driver.

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