fsl-usb: do not test for PHY_CLK_VALID bit on controller version 1.6

Per reference manuals of Freescale P1020 and P2020 SoCs, USB controller
present in these SoCs has bit 17 of USBx_CONTROL register marked as
Reserved - there is no PHY_CLK_VALID bit there.

Testing for this bit in ehci_fsl_setup_phy() behaves differently on two
P1020RDB boards available here - on one board test passes and fsl-usb
init succeeds, but on other board test fails, causing fsl-usb init to
fail.

This patch changes ehci_fsl_setup_phy() not to test PHY_CLK_VALID on
controller version 1.6 that (per manual) does not have this bit.

Signed-off-by: Nikita Yushchenko <nyushchenko@dev.rtsoft.ru>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>