use grep -s to suppress error messages about nonexistent or unreadable files
    
    Resolves: bz1895258
    Upstream: Fedora
    Conflict: None
    
    commit d5c31605f364e258fdef60e8482498941644ad6a
    Author: Coiby Xu <coxu@redhat.com>
    Date:   Thu Jan 6 09:48:17 2022 +0800
    
        use grep -s to suppress error messages about nonexistent or unreadable files
    
        When a file doesn't exist or isn't readable, grep complains as follows,
    
        grep: /proc/cmdline: No such file or directory
        grep: /etc/kernel/cmdline: No such file or directory
    
        /proc/cmdline doesn't exist when installing package for an OS image and
        /etc/kernel/cmdline may not exist if osbuild doesn't want set custom
        kernel cmdline.
    
        Use "-s" to suppress the error messages.
    
        Fixes: 0adb0f4 ("try to reset kernel crashkernel when kexec-tools updates the default crashkernel value")
        Fixes: ddd428a ("set up kernel crashkernel for osbuild in kernel hook")
        Signed-off-by: Coiby Xu <coxu@redhat.com>
        Acked-by: Tao Liu <ltao@redhat.com>
    
    Signed-off-by: Coiby Xu <coxu@redhat.com>