EX-7601 ofd: improve decompress_rnb debug

EX-7601 ofd: improve decompress_rnb debug

Since we're very close on landing the unaligned read
patches, this minor debug improvement is being placed later
in the series.

Test-Parameters: trivial
Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: I36ad243bd1f7025e358f9593f1008f0b851cc1bb
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/53411
Reviewed-by: Artem Blagodarenko <ablagodarenko@ddn.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>