USB: OHCI: Eliminate platform-specific test in ohci.h

The bcm63xx and bcm3384 platforms need to set OHCI_QUIRK_FRAME_NO, but
they are non-PPC platforms and don't enable CONFIG_PPC_MPC52xx.
Therefore this patch changes the code that uses OHCI_QUIRK_FRAME_NO,
making it not depend on CONFIG_PPC_MPC52xx.

Also, rephrase the comments describing OHCI_QUIRK_FRAME_NO and the
related PSW endian swap.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>