Add vendor hook to contorl blk plugging for shrink_lruvec. Merged CL bcf1e503f5ed774dc28126a0f1a8c839717eafac: ANDROID: adjust vendor hook to control blk_plug Bug: 255471591 Bug: 238728493 Change-Id: Iba2603ff2e1b62cf2ee8fd6969d8ccd71416a288 Signed-off-by: Minchan Kim <minchan@google.com> Signed-off-by: Richard Chang <richardycc@google.com> (cherry picked from commit 89fed37332fd48e0cd13b256cd85d6929d5da319)