ARM: shmobile: r8a7791: Correct SYS-DMAC clock defines

R-Car M2 has two MSTP bits for SYS-DMAC, not one.
Also bring the naming in sync with the documentation.

This issue was introduced in v3.14, in commit
4d8864c9 ("ARM: shmobile: r8a7791: Add
clock index macros for DT sources").
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

include/dt-bindings/clock/r8a7791-clock.h

@@ -43,7 +43,8 @@
 #define R8A7791_CLK_SCIFB1		7
 #define R8A7791_CLK_MSIOF1		8
 #define R8A7791_CLK_SCIFB2		16
-#define R8A7791_CLK_DMAC		18
+#define R8A7791_CLK_SYS_DMAC1		18
+#define R8A7791_CLK_SYS_DMAC0		19
 
 /* MSTP3 */
 #define R8A7791_CLK_TPU0		4