clk: samsung: exynos7: Add required clock tree for UFS

Adding required mux/div/gate clocks for UFS controller
present on Exynos7.

Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>