Use "UNUSED" to squash compiler warnings

Marlin/configuration_store.cpp

@@ -410,7 +410,7 @@ void Config_RetrieveSettings() {
 
     EEPROM_READ_VAR(i, dummy); // bedKp
     if (dummy != DUMMY_PID_VALUE) {
-      bedKp = dummy;
+      bedKp = dummy; UNUSED(bedKp);
       EEPROM_READ_VAR(i, bedKi);
       EEPROM_READ_VAR(i, bedKd);
     }
@@ -540,7 +540,7 @@ void Config_ResetDefault() {
     #if ENABLED(PID_PARAMS_PER_EXTRUDER)
       for (int e = 0; e < EXTRUDERS; e++)
     #else
-      int e = 0; // only need to write once
+      int e = 0; UNUSED(e); // only need to write once
     #endif
     {
       PID_PARAM(Kp, e) = DEFAULT_Kp;

Marlin/qr_solve.cpp

@@ -1024,7 +1024,7 @@ void dqrlss(double a[], int lda, int m, int n, int kr, double b[], double x[],
 
   if (kr != 0) {
     job = 110;
-    info = dqrsl(a, lda, m, kr, qraux, b, rsd, rsd, x, rsd, rsd, job);
+    info = dqrsl(a, lda, m, kr, qraux, b, rsd, rsd, x, rsd, rsd, job); UNUSED(info);
   }
 
   for (i = 0; i < n; i++)
@@ -1569,7 +1569,7 @@ void qr_solve(double x[], int m, int n, double a[], double b[])
   tol = r8_epsilon() / r8mat_amax(m, n, a_qr);
   itask = 1;
 
-  ind = dqrls(a_qr, lda, m, n, tol, &kr, b, x, r, jpvt, qraux, itask);
+  ind = dqrls(a_qr, lda, m, n, tol, &kr, b, x, r, jpvt, qraux, itask); UNUSED(ind);
 }
 /******************************************************************************/