UPSTREAM: erofs: use sync decompression for atomic contexts only

Sync decompression was introduced to get rid of additional kworker
scheduling overhead. But there is no such overhead in non-atomic
contexts. Therefore, it should be better to turn off sync decompression
to avoid the current thread waiting in z_erofs_runqueue.

Link: https://lore.kernel.org/r/20210317035448.13921-3-huangjianan@oppo.com


Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Guo Weichao <guoweichao@oppo.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>

Bug: 190585249
Change-Id: I7e03053d690b9cda4fe78c0ed0e2fbb0ba188d38
(cherry picked from commit 30048cda)
Signed-off-by: Huang Jianan <huangjianan@oppo.com>