Rename some (unused) OMCA pins

Marlin/pinsDebug_list.h

@@ -350,11 +350,11 @@
 #if PIN_EXISTS(HOME)
   REPORT_NAME_DIGITAL(HOME_PIN, __LINE__ )
 #endif
-#if defined(I2C_SCL) && I2C_SCL >= 0
+#if PIN_EXISTS(I2C_SCL)
-  REPORT_NAME_DIGITAL(I2C_SCL, __LINE__ )
+  REPORT_NAME_DIGITAL(I2C_SCL_PIN, __LINE__ )
 #endif
-#if defined(I2C_SDA) && I2C_SDA >= 0
+#if PIN_EXISTS(I2C_SDA)
-  REPORT_NAME_DIGITAL(I2C_SDA, __LINE__ )
+  REPORT_NAME_DIGITAL(I2C_SDA_PIN, __LINE__ )
 #endif
 #if PIN_EXISTS(KILL)
   REPORT_NAME_DIGITAL(KILL_PIN, __LINE__ )

Marlin/pins_OMCA.h

@@ -111,8 +111,8 @@
 //
 #define SDSS               11
 
-#define I2C_SCL            16
+#define I2C_SCL_PIN        16
-#define I2C_SDA            17
+#define I2C_SDA_PIN        17
 
 // future proofing
 #define __FS  20