Linux 4.19.81

Merge 91 patches from 4.19.81 stable
branch (94 total) beside 3 already merged patches:
9792afb mm/memory-failure.c: don't access uninitialized memmaps in memory_failure()
91eec76 hugetlbfs: don't access uninitialized memmaps in pfn_range_valid_gigantic()
27414f9 RDMA/cxgb4: Do not dma memory off of the stack
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

Makefile

 # SPDX-License-Identifier: GPL-2.0
 VERSION = 4
 PATCHLEVEL = 19
-SUBLEVEL = 80
+SUBLEVEL = 81
 EXTRAVERSION =
 NAME = "People's Front"