EX-7807 osc: don't discard decompress_request error

EX-7807 osc: don't discard decompress_request error

The error handling for decompress_request is unusual - non-zero
returns are just discarded. And rc2 is just discarded.
The read() doesn't fail or get a short read.

Fix this so if decompression fails with an error.

Reported-by: Patrick Farrell <pfarrell@whamcloud.com>
Signed-off-by: Artem Blagodarenko <ablagodarenko@ddn.com>
Fixes: f43b9ce9af ("EX-6127 osc: osc brw request compression")
Change-Id: Idd01947c7375c9586a64f064dd6ee0ac2308ea86
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51531
Tested-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>