fstab.common: Mount external usb storage am: c98a9afbc5

Original change: https://android-review.googlesource.com/c/device/linaro/dragonboard/+/2875514

Change-Id: Id1c9b10ce9283b13863c17709ad8bb6836e443e1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>