evdev: remove duplicate sizeof

This looks like a copy-and-paste error. In practice it was harmless on
64-bit systems because evdev_event happens to be 64 bits long, but on
32-bit systems it would allocate too little memory.

Found by GCC 15 with _FORTIFY_SOURCE=3 on ia32.

(cherry picked from commit 47d4c563f4)

Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1309>

src/evdev-frame.h

@@ -508,7 +508,7 @@ static inline struct evdev_frame *
 evdev_frame_new(size_t max_size)
 {
 	struct evdev_frame *frame =
-		zalloc(max_size * sizeof(sizeof(*frame->events)) + sizeof(*frame));
+		zalloc(max_size * sizeof(*frame->events) + sizeof(*frame));
 
 	frame->refcount = 1;
 	frame->max_size = max_size;