mm: remove PageOwnerPriv1

While there are many aliases for this flag, nobody actually uses the
*PageOwnerPriv1() nor folio_*_owner_priv_1() accessors.  Remove them.

Link: https://lkml.kernel.org/r/20240821193445.2294269-8-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/page-flags.h

@@ -539,8 +539,6 @@ FOLIO_FLAG(swapbacked, FOLIO_HEAD_PAGE)
  */
 PAGEFLAG(Private, private, PF_ANY)
 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
-PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
-	TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
 
 /*
  * Only test-and-set exist for PG_writeback.  The unconditional operators are