MAINTAINERS: Add Green as SiFive PDMA driver maintainer

Update MAINTAINERS for SiFive PDMA driver.
Signed-off-by: Green Wan <green.wan@sifive.com>
Link: https://lore.kernel.org/r/20191107084955.7580-5-green.wan@sifive.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

MAINTAINERS

@@ -14776,6 +14776,12 @@ F:	drivers/media/usb/siano/
 F:	drivers/media/usb/siano/
 F:	drivers/media/mmc/siano/
 
+SIFIVE PDMA DRIVER
+M:	Green Wan <green.wan@sifive.com>
+S:	Maintained
+F:	drivers/dma/sf-pdma/
+F:	Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
+
 SIFIVE DRIVERS
 M:	Palmer Dabbelt <palmer@sifive.com>
 M:	Paul Walmsley <paul.walmsley@sifive.com>