DIGIPOT_I2C pins for SMOOTHIEBOARD (#19098)

Marlin/src/pins/lpc1769/pins_SMOOTHIEBOARD.h

   #error "Marlin's Smoothieboard support cannot drive your LCD."
 
 #endif
+
+/**
+ * I2C Digipots - MCP4451
+ * Address 58 (2C << 1)
+ * Set from 0 - 127 with stop bit.
+ * (Ex. 3F << 1 | 1)
+ */
+#define DIGIPOTS_I2C_SCL                   P0_0
+#define DIGIPOTS_I2C_SDA_X                 P0_04
+#define DIGIPOTS_I2C_SDA_Y                 P0_10
+#define DIGIPOTS_I2C_SDA_Z                 P0_19
+#define DIGIPOTS_I2C_SDA_E0                P0_21
+#define DIGIPOTS_I2C_SDA_E1                P4_29
+
+#ifndef DIGIPOT_I2C_ADDRESS_A
+  #define DIGIPOT_I2C_ADDRESS_A             0x2C  // unshifted slave address (58 <- 2C << 1)
+#endif