treewide: remove references to CREDITS ...

The CREDITS file was removed from barebox in 2015 by commit 6570288f2d97
("Remove the CREDITS file"). Remove references to it from several files.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

usb: imx: implement support for limiting host to full speed ...

This is needed when host is known to not work properly in high speed
mode.

In linux, chipidea driver supports 'maximum-speed' device tree property.
When that is set to "full-speed", driver sets PFSC bit in PORTSC
register, which disallows use of high speed mode.

This patch implements same support for barebox.

Important technical detail is that PFSC bit is cleared by port reset,
thus setting it has to be done in ehci->init() callback which is called
after ehci_reset().

Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

USB: add usb phy header file ...

Mostly taken from the Linux Kernel to ease porting phy
handling code.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

USB: i.MX: Make DT dr_mode & phy_type parameters kernel compatible ...

Since the mainline kernel now has its own dr_mode and phy_type DT-options
for setting modes of USB ports, do these kernel parameters compatible by
removing "barebox" prefix.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

usb: Add devicetree helpers ...

Add helpers to get the dr_mode and the phy_mode.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>