vdsm: vdsmid: do not attempt to install dmidecode on platforms other than x86

Change-Id: Ib683ad399287f2a9502a2851557269cabeaded4d
Reported-By: Pradipta Kumar Banerjee <bpradip@in.ibm.com>
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>