MAINTAINERS: Mark RISC-V as Supported

There's at least two of us that are paid to work on this.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

MAINTAINERS

@@ -262,7 +262,7 @@ M: Alistair Francis <Alistair.Francis@wdc.com>
 M: Sagar Karandikar <sagark@eecs.berkeley.edu>
 M: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
 L: qemu-riscv@nongnu.org
-S: Maintained
+S: Supported
 F: target/riscv/
 F: hw/riscv/
 F: include/hw/riscv/