dt-bindings: phy: cadence-sierra: Add binding to specify SSC mode

Add binding to specify Spread Spectrum Clocking mode used

Signed-off-by: Swapnil Jakhade <sjakhade@cadence.com>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>

include/dt-bindings/phy/phy-cadence.h

@@ -17,4 +17,8 @@
 #define CDNS_SIERRA_PLL_CMNLC		0
 #define CDNS_SIERRA_PLL_CMNLC1		1
 
+#define SIERRA_SERDES_NO_SSC		0
+#define SIERRA_SERDES_EXTERNAL_SSC	1
+#define SIERRA_SERDES_INTERNAL_SSC	2
+
 #endif /* _DT_BINDINGS_CADENCE_SERDES_H */