Suppress some warnings

Marlin/src/gcode/config/M200-M205.cpp

@@ -61,7 +61,7 @@ void GcodeSuite::M201() {
 
   LOOP_XYZE(i) {
     if (parser.seen(axis_codes[i])) {
-      const uint8_t a = (i == E_AXIS ? E_AXIS_N(target_extruder) : i);
+      const uint8_t a = (i == E_AXIS ? uint8_t(E_AXIS_N(target_extruder)) : i);
       planner.settings.max_acceleration_mm_per_s2[a] = parser.value_axis_units((AxisEnum)a);
     }
   }
@@ -81,7 +81,7 @@ void GcodeSuite::M203() {
 
   LOOP_XYZE(i)
     if (parser.seen(axis_codes[i])) {
-      const uint8_t a = (i == E_AXIS ? E_AXIS_N(target_extruder) : i);
+      const uint8_t a = (i == E_AXIS ? uint8_t(E_AXIS_N(target_extruder)) : i);
       planner.settings.max_feedrate_mm_s[a] = parser.value_axis_units((AxisEnum)a);
     }
 }

Marlin/src/gcode/config/M92.cpp

@@ -40,6 +40,8 @@ void report_M92(const bool echo=true, const int8_t e=-1) {
       SERIAL_ECHOPAIR(" M92 T", (int)i);
       SERIAL_ECHOLNPAIR(" E", VOLUMETRIC_UNIT(planner.settings.axis_steps_per_mm[E_AXIS_N(i)]));
     }
+  #else
+    UNUSED(e);
   #endif
 }