phy: samsung: disable bind/unbind platform driver feature

Samsung PHY drivers control the power to the SoC core components needed by
their client devices (USB HCDs, SATA, camera ISP bridge, DP encoder) to
properly operate. Disabling PHYs in runtime usually causes the client
device to crash with external abort exception or similar issue due to lack
of API to notify clients about PHY removal. This patch removes the
possiblity to unbind Samsung Exynos PHY drivers in runtime.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>