sc: rename ScSTEXY to ScSTEYX

The actual Calc function is STEYX.

Change-Id: I7c778a3b00e54aa97b61c00e2e7c40c2db48a08b
Reviewed-on: https://gerrit.libreoffice.org/13898Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>

sc/source/core/inc/interpre.hxx

@@ -841,7 +841,7 @@ void ScCovarianceP();
 void ScCovarianceS();
 void ScPearson();
 void ScRSQ();
-void ScSTEXY();
+void ScSTEYX();
 void ScSlope();
 void ScTrend();
 void ScInfo();

sc/source/core/tool/interpr3.cxx

@@ -4254,7 +4254,7 @@ void ScInterpreter::ScRSQ()
     }
 }
 
-void ScInterpreter::ScSTEXY()
+void ScInterpreter::ScSTEYX()
 {
     CalculatePearsonCovar( true, true, false );
 }

sc/source/core/tool/interpr4.cxx

@@ -4185,7 +4185,7 @@ StackVar ScInterpreter::Interpret()
                 case ocCovarianceS      : ScCovarianceS();              break;
                 case ocPearson          : ScPearson();                  break;
                 case ocRSQ              : ScRSQ();                      break;
-                case ocSTEYX            : ScSTEXY();                    break;
+                case ocSTEYX            : ScSTEYX();                    break;
                 case ocSlope            : ScSlope();                    break;
                 case ocIntercept        : ScIntercept();                break;
                 case ocTrend            : ScTrend();                    break;