kdump-lib.sh: fix the case if no enough total RAM for kdump in get_recommend_size()
    
    Resolves: bz1952342
    Upstream: Fedora
    Conflict: None
    
    commit 45377836b014e22c27e5a210e679501f97ba4525
    Author: Pingfan Liu <piliu@redhat.com>
    Date:   Tue May 25 09:26:09 2021 +0800
    
        kdump-lib.sh: fix the case if no enough total RAM for kdump in get_recommend_size()
    
        For crashkernel=auto policy, if total RAM size is under a throttle,
        there is no memory reserved for kdump.
    
        Also correct a trivial bug by correcting the arch name.
    
        Signed-off-by: Pingfan Liu <piliu@redhat.com>
        Acked-by: Kairui Song <kasong@redhat.com>
    
    Signed-off-by: Pingfan Liu <piliu@redhat.com>