phy: exynos5-usbdrd: Add pipe-clk, utmi-clk and itp-clk support

Exynos7 SoC has now separate gate control for 125MHz pipe3 phy
clock, as well as 60MHz utmi phy clock.
Additionally, separate gate control is available for the clock
used for ITP (Isochronous Transfer Packet) generation.

So get the same and control in the phy-exynos5-usbdrd driver.

Suggested-by: Anton Tikhomirov <av.tikhomirov@samsung.com>
Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>