Fix bool++ warning

Marlin/src/feature/encoder_i2c.cpp

   encoderAxis = axis;
   i2cAddress = address;
 
-  initialized++;
+  initialized = true;
 
   SERIAL_ECHOLNPAIR("Setting up encoder on ", AS_CHAR(axis_codes[encoderAxis]), " axis, addr = ", address);
 
     delay(10);
 
     zeroOffset = get_raw_count();
-    homed++;
-    trusted++;
+    homed = trusted = true;
 
     #ifdef I2CPE_DEBUG
       SERIAL_CHAR(axis_codes[encoderAxis]);