powerpc: update kdumpctl to load kernel signing key for fadump
    
    Resolves: https://issues.redhat.com/browse/RHEL-14003
    Upstream: Fedora
    Conflict: None
    
    commit 4fa17b2ee4a6089cddd3c4b929840f4faf72ff98
    Author: Nayna Jain <nayna@linux.ibm.com>
    Date:   Tue Oct 3 23:41:47 2023 -0400
    
        powerpc: update kdumpctl to load kernel signing key for fadump
    
        On secure boot enabled systems with static keys, kexec with kexec_file_load(-s)
        fails as "Permission Denied" when fadump is enabled.
    
        Similar to kdump, load kernel signing key for fadump as well.
    
        Reported-by: Sachin P Bappalige <sachinpb@linux.vnet.ibm.com>
        Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
    
    Signed-off-by: Coiby Xu <coxu@redhat.com>