test: remove extra return

Clears warning from clang 19.1.7:

test/misc.c:239:12: warning: 'return' will never be executed
 [-Wunreachable-code-return]
  239 |     return 0;

Fixes: 46b579e8d ("test: switch the unit tests to something resembling a test suite")
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1910>

test/misc.c

@@ -235,6 +235,4 @@ misc_test(void)
         NULL,
     };
     return testfuncs;
-
-    return 0;
 }