There is a long-standing bug that OHCI USB host controller does
not respond on 1710, because of wrong clock definitions. See e.g.
http://marc.info/?l=linux-omap&m=119634441229321&w=2. All register reads
return just zeroes:

[    1.896606] ohci ohci: OMAP OHCI
[    1.912597] ohci ohci: new USB bus registered, assigned bus number 1
[    1.933776] ohci ohci: irq 38, io mem 0xfffba000
[    2.012573] ohci ohci: init err (00000000 0000)
[    2.030334] ohci ohci: can't start
[    2.046661] ohci ohci: startup error -75
[    2.063201] ohci ohci: USB bus 1 deregistered

After some experiments, it seems that when changing the usb_dc_ck /
SOFT_REQ enable bit from USB_REQ_EN_SHIFT to SOFT_USB_OTG_DPLL_REQ_SHIFT
(like done also on 7XX), the USB appears to work:

[    2.183959] ohci ohci: OMAP OHCI
[    2.198242] ohci ohci: new USB bus registered, assigned bus number 1
[    2.215820] ohci ohci: irq 38, io mem 0xfffba000
[    2.324798] hub 1-0:1.0: USB hub found
[    2.361267] hub 1-0:1.0: 3 ports detected

The patch is tested on Nokia 770.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Paul Walmsley <paul@pwsan.com>