dracut-module-setup.sh: remove surrounding $() for subshell
    
    upstream: fedora
    resolves: bz2003832
    conflict: none
    
    commit 3b0157197b4dcc7c06487d5f44395317c5f4670f
    Author: Kairui Song <kasong@redhat.com>
    Date:   Wed Sep 8 15:15:44 2021 +0800
    
        dracut-module-setup.sh: remove surrounding $() for subshell
    
        Some functions are executed in subshell to avoid variable environment
        pollution. But the surrounding $() is not needed, and it may lead to
        executing output which is unexpected here.
    
        See: https://github.com/koalaman/shellcheck/wiki/SC2091
    
        Signed-off-by: Kairui Song <kasong@redhat.com>
        Suggested-by: Coiby Xu <coxu@redhat.com>
    
    Signed-off-by: Tao Liu <ltao@redhat.com>