hello charles,
You have to look into your kernel's configuration, to enable the USB part...
In LTIB check "configure the kernel" exit and save your new configuration . . .
Afterward the linux kernel configuration appear, go into "device drivers">"USB support"
Enable as much things as you need.
Be sure that "EHCI HCD USB2.0" | "support for ARC controller" | "Support for Host1" port on ARC controller" |"USB mass storage support" | are built-in (the star symbol).
If you ever try to use the host 2 you have to check if you are not using your pins for another function, because a lot of things are multiplexed . . .
exit and save and flash your board with the new kernel
with the host 1 enable you should be able to mount a usb mass storage on the USB Host 1 FS port...
enjoy
good luck
aurelien