sdcardfs: Check for other cases on path lookup

This fixes a bug where the first lookup of a
file or folder created under a different view
would not be case insensitive. It will now
search through for a case insensitive match
if the initial lookup fails.

Bug:28024488
Change-Id: I4ff9ce297b9f2f9864b47540e740fd491c545229
Signed-off-by: Daniel Rosenberg <drosen@google.com>