LU-12511 lov: use lov_pattern_support() to verify lmm

LU-12511 lov: use lov_pattern_support() to verify lmm

We can use lov_pattern_support(), which is used by the server
and userland code, to ensure lmm is valid instead of open coding.

Change-Id: I44051e6e2dba2f0b7e481572bb58d776724aecd8
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/38791
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>