riscv: Move Andes PLMT driver to drivers/timer

This is a regular timer driver, and should live with the other timer
drivers.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Rick Chen <rick@andestech.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index fc4fad4..5d02235 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -938,6 +938,7 @@
 T:	git https://gitlab.denx.de/u-boot/custodians/u-boot-riscv.git
 F:	arch/riscv/
 F:	cmd/riscv/
+F:	drivers/timer/andes_plmt_timer.c
 F:	tools/prelink-riscv.c
 
 RISC-V KENDRYTE