USB: less-restrictive command checking in g-file-storage

This patch (as983) makes a test for minimum-length command sizes in
g_file_storage less restrictive.  It doesn't matter because commands
with bad lengths will be detected later on anyway, and doing it like
this makes the driver interoperable with certain buggy hosts such as
the JVC HiFi (reported by Samuel Hangouet).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>