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.

Test-Parameters: trivial
Change-Id: I2af307ee87448faeec81f6e0e27573ae980710f1
Signed-off-by: Aurelien Degremont <adegremont@nvidia.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/52951
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Colin Faber <cfaber@ddn.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>