EX-9873 obdclass: reset bits after decompression

EX-9873 obdclass: reset bits after decompression

as uncompressed data can be less than chunk/page, but still be
visiable to userspace as a part of a sparse file.

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I4114b0704fb685013f4e03cf2d80ccde2cc8c87f
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/55308
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Artem Blagodarenko <ablagodarenko@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>