Add this option as a common config for all OHCI controllers. Its
help message was copied from Linux. Also, I moved it below EHCI
to respect the order in Linux's Kconfig.
Add CONFIG_USB_OHCI_HCD=y to axs103_defconfig, which is the only
user of OHCI_GENERIC.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>