spi: Move mailing list to vger

Given the spam and other problems with the existing list move to a newly
created list on vger.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

MAINTAINERS

@@ -7589,7 +7589,7 @@ F:	drivers/clk/spear/
 SPI SUBSYSTEM
 M:	Mark Brown <broonie@kernel.org>
 M:	Grant Likely <grant.likely@linaro.org>
-L:	spi-devel-general@lists.sourceforge.net
+L:	linux-spi@vger.kernel.org
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git
 Q:	http://patchwork.kernel.org/project/spi-devel-general/list/
 S:	Maintained