mm: remove unused TestSetPageLocked() interface

TestSetPageLocked() isn't being used anywhere.  Also, using it would
likely be an error, since the proper interface trylock_page() provides
stronger ordering guarantees.
Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/page-flags.h

@@ -196,7 +196,7 @@ static inline int __TestClearPage##uname(struct page *page) { return 0; }
 
 struct page;	/* forward declaration */
 
-TESTPAGEFLAG(Locked, locked) TESTSETFLAG(Locked, locked)
+TESTPAGEFLAG(Locked, locked)
 PAGEFLAG(Error, error) TESTCLEARFLAG(Error, error)
 PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
 PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)