phy: exynos5-usbdrd: add exynos7870 USBDRD support

phy: exynos5-usbdrd: add exynos7870 USBDRD support

Implement support for Exynos7870 USB DRD on top of the existing
exynos5-usbdrd driver.

Exynos7870 has a single USB 2.0 DRD PHY controller and no 3.0 PHYs. Thus,
it only supports the UTMI interface.

Moreover, the PMU register offset for enabling the PHY controller is
different for SoCs such as Exynos7870, where BIT(0) is for the 3.0 PHY and
BIT(1) is for the 2.0 PHY. The phy_isol function for Exynos7870 uses the
appropriate register offsets.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Link: https://lore.kernel.org/r/20250410-exynos7870-usbphy-v2-3-2eb005987455@disroot.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>