Re-add module description for ms02-nv to Kconfig

In an unrelated MTD commit, a description about the ms02-nv module
got removed from Kconfig.  While I personally agree with this
removal, the module maintainer (Maciej W. Rozycki) would like to
see it added back.  In the absense of any consistency regarding
Kconfig descriptions his wish should be followed.

Signed-off-by: Martin Michlmayr <tbm@cyrius.com>
Acked-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>