speakup: fix uninitialized flush_lock

The flush_lock is uninitialized, use DEFINE_SPINLOCK
to define and initialize flush_lock.

Fixes: c6e3fd22cd53 ("Staging: add speakup to the staging directory")
Reported-by: Hulk Robot <[e-mail]>
Reviewed-by: Samuel Thibault <[e-mail]>
Signed-off-by: Yang Yingliang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/accessibility/speakup/speakup_dectlk.c

···
 static int in_escape;
 static int is_flushing;
 
-static spinlock_t flush_lock;
+static DEFINE_SPINLOCK(flush_lock);
 static DECLARE_WAIT_QUEUE_HEAD(flush);
 
 static struct var_t vars[] = {