EX-7601 osc: allow multiple chunks in read

EX-7601 osc: allow multiple chunks in read

It's rare, but reads can sometimes have multiple
discontiguous chunks.  Update decompress_request to
handle this case.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: I880af95db285dce76db3610e8140a0f54baa401b
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/53159
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>