ANDROID: mm/filemap: Fix missing put_page() for speculative page fault

find_get_page() returns a page with increased refcount, assuming a page
exists at the given index. Ensure this refcount is dropped on error.

Bug: 271079833
Bug: 295789791
Fixes: 59d4d125 ("BACKPORT: FROMLIST: mm: implement speculative handling in filemap_fault()")
Change-Id: Idc7b9e3f11f32a02bed4c6f4e11cec9200a5c790
Signed-off-by: Patrick Daly <quic_pdaly@quicinc.com>
(cherry picked from commit 6232eecf)
Signed-off-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
(cherry picked from commit 1d052130)
(cherry picked from commit 6b86d523)