[PATCH] fix semaphore handling in __unregister_chrdev_region

This up() should be down() instead.

Signed-off-by: Wen-chien Jesse Sung <jesse@cola.voip.idv.tw>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>