mfd: intel-lpss: Remove left over variable

After commit 028af594 ("mfd: intel-lpss: Pass SDA hold time to
I2C host controller driver") the driver still has a non-used variable.

Remove it here.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>