LU-18871 dkms: prefer 'command -v' over 'which'

LU-18871 dkms: prefer 'command -v' over 'which'

Prefer command -v over which to quash spurious output during
dkms build.

Test-Parameters: trivial testgroup=full-dkms
HPE-bug-id: LUS-12801
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: I63494f0bbb16c5dff85fcac2e8cb9c141c38bdd2
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58594
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alexander Zarochentsev <alexander.zarochentsev@hpe.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>