ARM: socfpga: fix uart DMA binding error

socfpga.dtsi is missing the DMA channels for the uart nodes.
This will produce the following errors:

	of_dma_request_slave_channel: dma-names property of node '/soc/serial0@ffc02000' missing or empty
	ttyS0 - failed to request DMA

Provide the correct DMA channels to fix this.
Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>

arch/arm/boot/dts/socfpga.dtsi

@@ -713,6 +713,9 @@ uart0: serial0@ffc02000 {
 			reg-shift = <2>;
 			reg-io-width = <4>;
 			clocks = <&l4_sp_clk>;
+			dmas = <&pdma 28>,
+			       <&pdma 29>;
+			dma-names = "tx", "rx";
 		};
 
 		uart1: serial1@ffc03000 {
@@ -722,6 +725,9 @@ uart1: serial1@ffc03000 {
 			reg-shift = <2>;
 			reg-io-width = <4>;
 			clocks = <&l4_sp_clk>;
+			dmas = <&pdma 30>,
+			       <&pdma 31>;
+			dma-names = "tx", "rx";
 		};
 
 		rst: rstmgr@ffd05000 {