Add 'console=tty0 quiet' to cmdline for aarch64 installs
    
    We need this as part of the fix for #1593028, at least until
    the kernel package is changed to no longer have
    CONFIG_CMDLINE="console=ttyAMA0" in the config for aarch64
    builds. Fully fixing the bug also requires some change to the
    kernel or dracut or something.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>