MAINTAINERS: move the staging subsystem to lists.linux.dev

The drivers/staging/ tree has a new mailing list,
linux-staging@lists.linux.dev, so move the MAINTAINER entry to point to
it so that we get patches sent to the proper place.

There was no need to specify a list for the hikey9xx driver, the tools
pick up the "base" list for drivers/staging/* so remove that line to
make the file simpler.

Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/20210316102311.182375-1-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -8116,7 +8116,6 @@ F:	drivers/crypto/hisilicon/sec2/sec_main.c
 
 HISILICON STAGING DRIVERS FOR HIKEY 960/970
 M:	Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
-L:	devel@driverdev.osuosl.org
 S:	Maintained
 F:	drivers/staging/hikey9xx/
 
@@ -17040,7 +17039,7 @@ F:	drivers/staging/vt665?/
 
 STAGING SUBSYSTEM
 M:	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-L:	devel@driverdev.osuosl.org
+L:	linux-staging@lists.linux.dev
 S:	Supported
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
 F:	drivers/staging/