omap1: omap_udc: Add clocking and disable vbus sense for omap7xx

The l3_ocpi_ck clock is needed on omap7xx processors for USB.
Additionally, bit 8 of the SOFT_REQ_REG needs to be enabled for
the usb_dc_ck on omap7xx, which is a different bit than that
of the omap16xx-defined clock of the same name.

I added a provision for the usb_dc_ck and l3_ocpi_ck clocks as
dc_clk and hhc_clk, respectively, for omap7xx CPUs.  Additionally,
I added a check in machine_without_vbus_sense for all omap7xx
devices, as presently I know of no omap7xx-based devices that
have vbus sense, and it made more sense to me to use a cpu check
here than to spell out each machine one at a time.  Finally, DMA
is disabled for omap7xx, as it causes problems with these chips.

Cc: linux-usb@vger.kernel.org
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>