try to update the crashkernel in GRUB_ETC_DEFAULT after kexec-tools updates the default crashkernel value
    
    Upstream: fedora
    Conflict: none
    Resolves: bz2060774
    
    commit 6d4062a936694b7cab7e0c536414b4d5b6ab8668
    Author: Coiby Xu <coxu@redhat.com>
    Date:   Wed Feb 16 09:42:54 2022 +0800
    
        try to update the crashkernel in GRUB_ETC_DEFAULT after kexec-tools updates the default crashkernel value
    
        If GRUB_ETC_DEFAULT use crashkernel=auto or
        crashkernel=OLD_DEFAULT_CRASHKERNEL, it should be updated as well.
    
        Add a helper function to read kernel cmdline parameter from
        GRUB_ETC_DEFAULT. This function is used to read kernel cmdline
        parameter like fadump or crashkernel.
    
        Reviewed-by: Philipp Rudo <prudo@redhat.com>
    
    Signed-off-by: Tao Liu <ltao@redhat.com>