[Blackfin] arch: Enable UART2 and UART3 for bf548

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/include/asm-blackfin/mach-bf548/dma.h b/include/asm-blackfin/mach-bf548/dma.h
index 4d97d3a..46ff31f 100644
--- a/include/asm-blackfin/mach-bf548/dma.h
+++ b/include/asm-blackfin/mach-bf548/dma.h
@@ -51,9 +51,13 @@
 #define CH_PIXC_OVERLAY		16
 #define CH_PIXC_OUTPUT		17
 #define CH_SPORT2_RX		18
+#define CH_UART2_RX		18
 #define CH_SPORT2_TX		19
+#define CH_UART2_TX		19
 #define CH_SPORT3_RX		20
+#define CH_UART3_RX		20
 #define CH_SPORT3_TX		21
+#define CH_UART3_TX		21
 #define CH_SDH			22
 #define CH_NFC			22
 #define CH_SPI2			23