Various shell files contain a mix between obsolete ``
and modern $(); It would be nice to convert to using $()
everywhere.

Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>