ui/cocoa: Use macro ARRAY_SIZE where possible

This improves readability and simplifies the code.

Cc: Andreas Färber <andreas.faerber@web.de>
Cc: Anthony Liguori <aliguori@amazon.com>
Signed-off-by: NStefan Weil <sw@weilnetz.de>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

ui/cocoa.m

@@ -240,9 +240,8 @@ int keymap[] =
 
 static int cocoa_keycode_to_qemu(int keycode)
 {
-    if((sizeof(keymap)/sizeof(int)) <= keycode)
-    {
-        printf("(cocoa) warning unknow keycode 0x%x\n", keycode);
+    if (ARRAY_SIZE(keymap) <= keycode) {
+        printf("(cocoa) warning unknown keycode 0x%x\n", keycode);
         return 0;
     }
     return keymap[keycode];