Instead rely on device tree information for ehci and ohci.

This was suggested with
http://www.linux-mips.org/cgi-bin/mesg.cgi?a=linux-mips&i=1401358203-60225-4-git-send-email-alex.smith%40imgtec.com

  "The device tree will *always* have correct ehci/ohci clock
  configuration, so use it.  This allows us to remove a big chunk of
  platform configuration code from octeon-platform.c."

More or less I rebased that patch on Alan's work to remove ehci-octeon
and ohci-octeon drivers.

Cc: David Daney <david.daney@cavium.com>
Cc: Alex Smith <alex.smith@imgtec.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: NAndreas Herrmann <andreas.herrmann@caviumnetworks.com>
Acked-by: NRalf Baechle <ralf@linux-mips.org>
Tested-by: NAaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>