MAINTAINERS: Change Solarflare maintainers

Email from solarflare.com will stop working. Update the maintainers.
A replacement for linux-net-drivers@solarflare.com is not working yet,
for now remove it.

Signed-off-by: Martin Habets <mhabets@solarflare.com>
Signed-off-by: Edward Cree <ecree@solarflare.com>
Link: https://lore.kernel.org/r/20201120113207.GA1605547@mh-desktop
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

MAINTAINERS

@@ -15775,9 +15775,8 @@ F:	drivers/slimbus/
 F:	include/linux/slimbus.h
 
 SFC NETWORK DRIVER
-M:	Solarflare linux maintainers <linux-net-drivers@solarflare.com>
-M:	Edward Cree <ecree@solarflare.com>
-M:	Martin Habets <mhabets@solarflare.com>
+M:	Edward Cree <ecree.xilinx@gmail.com>
+M:	Martin Habets <habetsm.xilinx@gmail.com>
 L:	netdev@vger.kernel.org
 S:	Supported
 F:	drivers/net/ethernet/sfc/