JFFS2: drop support for LZARI compression mode

Support for LZARI compression mode was added based on a MTD CVS
snapshot of March 13, 2005. However, fs/jffs2/compr_lzari.c contains
contradictory licensing terms: the original copyright clause says "All
rights reserved. Permission granted for non-commercial use.", but
later reference to the file 'LICENCE' in the jffs2 directory was added
which says GPL v2 or later.

As no boards ever used LZARI compression, and this file is also not
present in recent MTD code, we resolve this conflict by removing the
conflicting file and references to it.

Also copy the referenced but missing file 'LICENCE' from the current
MTD source tree.

Signed-off-by: Wolfgang Denk <wd@denx.de>