LU-17256 debian: allow building client dkms on arm64

LU-17256 debian: allow building client dkms on arm64

Just add 'arm64' on the supported architecture list
for 'lustre-client-modules-dkms' debian package.

Lustre-change: https://review.whamcloud.com/52951
Lustre-commit: c4c9a8eea31cf9aa02f75ca3f119f90d67c70cc5

Test-Parameters: trivial
Change-Id: I2af307ee87448faeec81f6e0e27573ae980710f1
Signed-off-by: Aurelien Degremont <adegremont@nvidia.com>
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/53023
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Colin Faber <cfaber@ddn.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>