Revert "ARM: OMAP2+: Provide alias to USB PHY clock"

This reverts commit 741532c4a995be11815cb72d4d7a48f442a22fea.

The proper clock reference is provided in device tree so we
no longer need this.

Signed-off-by: Roger Quadros <rogerq@ti.com>
ARM: OMAP2+: defconfig: Enable USB EHCI host driver

Enable EHCI host controller driver.

Signed-off-by: Roger Quadros <rogerq@ti.com>