Remove matrix size defines (#19581)

keyboards/spaceholdings/nebula12b/config.h

@@ -18,10 +18,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #pragma once
 
 
-/* key matrix size */
-#define MATRIX_ROWS 4
-#define MATRIX_COLS 3
-
 #define MATRIX_ROW_PINS { B7, B4, F7, F6 }
 #define MATRIX_COL_PINS { F4, F5, D7 }