mfd: intel-lpss: Add support for ADL-P i2c6 and i2c7

Added 8086:51d8 and 8086:51d9 to the intel_lpss_pci driver. They are
Intel Alder Lake-P i2c controllers.

Signed-off-by: Gaggery Tsai <gaggery.tsai@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220520193537.26090-1-gaggery.tsai@intel.com