phy: intel-lgm-emmc: Add support for eMMC PHY

Add support for eMMC PHY on Intel's Lightning Mountain SoC.

Signed-off-by: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>