usb: otg: OMAP4: Fix the omap4430_phy_set_clk function

usb: otg: OMAP4: Fix the omap4430_phy_set_clk function

If the clocks are enabled and we want to enable them again
omap4430_phy_set_clk disables them.

Fix this - so now if we try to enable already enabled clocks
it works correctly.

Change-Id: I657e13651c908eaa7caf2fd4ff86028c50902fd6
Signed-off-by: Ruslan Bilovol <ruslan.bilovol@ti.com>