MCP4451 Digipot Support for Azteeg X5 GT (#21680)

Marlin/src/feature/digipot/digipot_mcp4451.cpp

 #elif MB(AZTEEG_X5_MINI, AZTEEG_X5_MINI_WIFI)
   #define DIGIPOT_I2C_FACTOR      113.5f
   #define DIGIPOT_I2C_MAX_CURRENT   2.0f
+#elif MB(AZTEEG_X5_GT)
+  #define DIGIPOT_I2C_FACTOR       51.0f
+  #define DIGIPOT_I2C_MAX_CURRENT   3.0f
 #else
   #define DIGIPOT_I2C_FACTOR      106.7f
   #define DIGIPOT_I2C_MAX_CURRENT   2.5f

Marlin/src/inc/SanityCheck.h

 #if HAS_MOTOR_CURRENT_I2C
   #if BOTH(DIGIPOT_MCP4018, DIGIPOT_MCP4451)
     #error "Enable only one of DIGIPOT_MCP4018 or DIGIPOT_MCP4451."
-  #elif !MB(MKS_SBASE) \
+#elif !MB(MKS_SBASE, AZTEEG_X5_GT, AZTEEG_X5_MINI, AZTEEG_X5_MINI_WIFI) \
     && (!defined(DIGIPOTS_I2C_SDA_X) || !defined(DIGIPOTS_I2C_SDA_Y) || !defined(DIGIPOTS_I2C_SDA_Z) || !defined(DIGIPOTS_I2C_SDA_E0) || !defined(DIGIPOTS_I2C_SDA_E1))
       #error "DIGIPOT_MCP4018/4451 requires DIGIPOTS_I2C_SDA_* pins to be defined."
   #endif