axs10x: add support of generic EHCI USB 2.0 controller

This commit adds support of USB 2.0 storage media on AXS10x boards.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Simon Glass <sjg@chromium.org>