Since 'cmdline, NULL' is now a default for parse_mtd_partitions, don't specify
this in every driver, instead pass NULL to force parse_mtd_partitions
to use default.

Artem: tweaked the patch
Signed-off-by: NDmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>