dt-bindings: Remove VSC8531 specific RGMII delay definitions

Based on Linux upstream discussion value enumeration shouldn't be used.
Instead of it delay in pS should be used that's why remove it from the
header.

Link: https://lore.kernel.org/all/YNsm%2F0dmpBgO8mqr@lunn.ch/
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/bbd343474856a67252f3b31d22b3b5a80ad04043.1698851109.git.michal.simek@amd.com
diff --git a/include/dt-bindings/net/mscc-phy-vsc8531.h b/include/dt-bindings/net/mscc-phy-vsc8531.h
index 61f5287..c340437 100644
--- a/include/dt-bindings/net/mscc-phy-vsc8531.h
+++ b/include/dt-bindings/net/mscc-phy-vsc8531.h
@@ -28,13 +28,4 @@
 #define VSC8531_FORCE_LED_OFF			14
 #define VSC8531_FORCE_LED_ON			15
 
-#define VSC8531_RGMII_CLK_DELAY_0_2_NS	0
-#define VSC8531_RGMII_CLK_DELAY_0_8_NS	1
-#define VSC8531_RGMII_CLK_DELAY_1_1_NS	2
-#define VSC8531_RGMII_CLK_DELAY_1_7_NS	3
-#define VSC8531_RGMII_CLK_DELAY_2_0_NS	4
-#define VSC8531_RGMII_CLK_DELAY_2_3_NS	5
-#define VSC8531_RGMII_CLK_DELAY_2_6_NS	6
-#define VSC8531_RGMII_CLK_DELAY_3_4_NS	7
-
 #endif