EX-7729 osc: Do not iterate over chunk pages

EX-7729 osc: Do not iterate over chunk pages

If osc_decompress() knows chunk size, no need to iterate
other all pages in chunk. Thay can be skipped.

Signed-off-by: Artem Blagodarenko <ablagodarenko@ddn.com>
Change-Id: Ib84b060075c55c97eba9f74ef017c0a956e85b12
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/54270
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Vitaliy Kuznetsov <vkuznetsov@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>