keyboard: Refactor status validation.

Reuse the maple enum function that already validates
a device and status prior to returning it.

Author: QuzarDC

kernel/arch/dreamcast/hardware/maple/keyboard.c

@@ -534,16 +534,12 @@ int kbd_get_key(void) {
 }
 
 kbd_state_t *kbd_get_state(maple_device_t *device) {
-    if(!device)
-        return NULL;
-
-    if(!device->status)
-        return NULL;
+    kbd_state_t *state = (kbd_state_t *)maple_dev_status(device);
 
-    if(!(device->info.functions & MAPLE_FUNC_KEYBOARD))
+    if(!state || !(device->info.functions & MAPLE_FUNC_KEYBOARD))
         return NULL;
 
-    return (kbd_state_t *)device->status;
+    return state;
 }
 
 /* Take a key off of a specific key queue. */