fsl/usb: Resolve PHY_CLK_VLD instability issue for ULPI phy

commit ad1260e9fbf768d6bed227d9604ebee76a84aae3 upstream.

For controller versions greater than 1.6, setting ULPI_PHY_CLK_SEL
bit when USB_EN bit is already set causes instability issues with
PHY_CLK_VLD bit. So USB_EN is set only for IP controller version
below 1.6 before setting ULPI_PHY_CLK_SEL bit

Signed-off-by: Ramneek Mehresh <ramneek.mehresh@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>