usb: ehci: rmobile: Remove xHCI address

echi-rmobile does not support xHCI. This removes xHCI address
from address table. And this revise a value of CONFIG_USB_MAX_CONTROLLER_COUNT
for lager board and koelsh board.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>