dt-bindings: clk: add missing clk ids for microchip mpfs

When this binding header was initally upstreamed, the PLL clocking the
microprocessor subsystem (MSS) and the RTC reference clocks were
omitted. Add them now, matching the IDs used in Linux.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
Reviewed-by: Padmarao Begari <padmarao.begari@microchip.com>
diff --git a/include/dt-bindings/clock/microchip-mpfs-clock.h b/include/dt-bindings/clock/microchip-mpfs-clock.h
index 55fe646..c7ed0a8 100644
--- a/include/dt-bindings/clock/microchip-mpfs-clock.h
+++ b/include/dt-bindings/clock/microchip-mpfs-clock.h
@@ -42,4 +42,7 @@
 #define CLK_ATHENA	31
 #define CLK_CFM		32
 
+#define CLK_RTCREF	33
+#define CLK_MSSPLL	34
+
 #endif	/* _DT_BINDINGS_CLK_MICROCHIP_MPFS_H_ */