Crostini USB settings page ui tweaks

Capitalized USB, changed list to use 'list-item'
class which removes top line from first list item.

Bug: 951519
Change-Id: I0aebf186bd8d6ecd44c4f7b86977a7594c982142
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1563590
Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Auto-Submit: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Nicholas Verne <nverne@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653048}
2 files changed