Migrate dynamic_keymap.layer_count < 4 where requried (#22091)

Co-authored-by: Nick Brassel <nick@tzarc.org>

keyboards/fc980c/config.h

@@ -17,10 +17,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #pragma once
 
-
-/* Maximum dynamic keymap layers (constrained by EEPROM space) */
-#define DYNAMIC_KEYMAP_LAYER_COUNT 3
-
 /* key matrix size */
 #define MATRIX_ROWS 8
 #define MATRIX_COLS 16

keyboards/fc980c/info.json

@@ -8,6 +8,9 @@
     "pid": "0x980C",
     "device_version": "1.0.0"
   },
+  "dynamic_keymap": {
+    "layer_count": 3
+  },
   "indicators": {
     "caps_lock": "B5",
     "num_lock": "B4",