MAINTAINERS: update NETWORK and NETWORK (LWIP)

Add myself as a maintainer of the NETWORK subsystem since:
- I have effectively been handling net patches in my patchwork queue and
sending pull requests to Tom,
- I do have push access to the u-boot-net custodian tree.

Also, add u-boot-net as the SCM tree for NETWORK (LWIP) since it is where
lwIP-related patches end up too.

Signed-off-by: Jerome Forissier <[email protected]>
CC: Ramon Fried <[email protected]>
CC: Joe Hershberger <[email protected]>
CC: Tom Rini <[email protected]>

Author: jforissier

MAINTAINERS

@@ -1414,6 +1414,7 @@ F:	drivers/mmc/
 NETWORK
 M:	Joe Hershberger <[email protected]>
 M:	Ramon Fried <[email protected]>
+M:	Jerome Forissier <[email protected]>
 S:	Maintained
 T:	git https://source.denx.de/u-boot/custodians/u-boot-net.git
 F:	drivers/net/
@@ -1423,6 +1424,7 @@ F:	net/
 NETWORK (LWIP)
 M:	Jerome Forissier <[email protected]>
 S:	Maintained
+T:	git https://source.denx.de/u-boot/custodians/u-boot-net.git
 F:	cmd/lwip/
 F:	cmd/net-lwip.c
 F:	configs/qemu_arm64_lwip_defconfig