kdump: Fix required kexec-tools versions

Fixes required kexec-tools versions to RPMs provided on oVirt
repositories so kdump detection feature will be available for RHEL 6/7
host before RHEL 6.6/7.1 release.

Change-Id: I807f308d22616dd044a1318339564d3a7ebbb1e9
Bug-Url: https://bugzilla.redhat.com/1079821
Signed-off-by: Martin Perina <mperina@redhat.com>