LU-18987 mdt: Remove stray assertion for dom read

LU-18987 mdt: Remove stray assertion for dom read

There's a strange assertion in mdt_dom_read_on_open()
that does not make sense and checks parameters in
a loop that don't even change.

Let's remove it.

Change-Id: I0662b621a39fbde79415676a8486ec4f9ab3a2ab
Test-Parameters: trivial
Fixes: 13372d6c243c ("LU-10181 mdt: read on open for DoM files")
Signed-off-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/59173
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Mikhail Pershin <mpershin@whamcloud.com>