uboot-imx

usb: r8a66597: Fix initialization hub that using R8A66597_MAX_ROOT_HUB

This driver is processed as two USB hub despite one.
The number of root hub is defined in R8A66597_MAX_ROOT_HUB.
This fixes that register is accessed by using the definition
of R8A66597_MAX_ROOT_HUB.

Signed-off-by: Yasuhisa Umano <yasuhisa.umano.zc@renesas.com>