fwk: Remove unimplemented FN+S

There is no need for the FN+S shortcut.

The PRT SCR key works as sysrq.
This is the same as on QMK with `KC_PRINT_SCREEN`

```
> sudo libinput debug-events --show-keycodes | grep KEYBOARD_KEY
-event2   KEYBOARD_KEY                 +4.295s  KEY_SYSRQ (99) pressed
 event2   KEYBOARD_KEY                 +0.067s  KEY_SYSRQ (99) released
```

BUG=Customer was asking why FN+S wasn't working.
BRANCH=fwk-main
TEST=`zmake build marigold`

Signed-off-by: Daniel Schaefer <dhs@frame.work>
Co-authored-by: Quin Chou <chc@frame.work>
(cherry picked from commit 281d6ba)

Author: JohnAZoidberg

zephyr/program/framework/src/keyboard_customization_13.c

@@ -323,12 +323,7 @@ int hotkey_F1_F12(uint16_t *key_code, uint16_t fn, int8_t pressed)
 		}
 		break;
 	case SCANCODE_F11:
-			/*
-			 * TODO this might need an
-			 * extra key combo of:
-			 * 0xE012 0xE07C to simulate
-			 * PRINT_SCREEN
-			 */
+		/* Print screen / SYSRQ */
 		if (fn_table_media_set(pressed, KB_FN_F11))
 			*key_code = 0xE07C;
 		break;
@@ -357,10 +352,6 @@ int hotkey_special_key(uint16_t *key_code, int8_t pressed)
 		if (fn_table_set(pressed, KB_FN_K))
 			*key_code = SCANCODE_SCROLL_LOCK;
 		break;
-	case SCANCODE_S:  /* TODO: SYSRQ */
-		/*if (!fn_table_set(pressed, KB_FN_S))*/
-
-		break;
 	case SCANCODE_LEFT:  /* HOME */
 		if (fn_table_set(pressed, KB_FN_LEFT))
 			*key_code = 0xe06c;