Update the RISC-V MAINTAINERS file

Now that we're upstream in Linux we've been able to make some
infrastructure changes so our port works a bit more like other ports.
Specifically:

* We now have a mailing list specific to the RISC-V Linux port, hosted
at lists.infreadead.org.
* We now have a kernel.org git tree where work on our port is
coordinated.

This patch changes the RISC-V maintainers entry to reflect these new
bits of infrastructure.

Reviewed-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Palmer Dabbelt <[e-mail]>

MAINTAINERS

···
 RISC-V ARCHITECTURE
 M:	Palmer Dabbelt <[e-mail]>
 M:	Albert Ou <[e-mail]>
-L:	[e-mail]
-T:	git https://github.com/riscv/riscv-linux
+L:	[e-mail]
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux.git
 S:	Supported
 F:	arch/riscv/
 K:	riscv