spec: fix systemd-tmpfiles-setup.service failure

spec: fix systemd-tmpfiles-setup.service failure

systemd-tmpfiles-setup.service is failed since
/usr/share/factory/etc/nsswitch.conf is not installed. This patch fixes
that bug by adding /usr/share/factory/etc/nsswitch.conf into systemd
package. If /etc/nsswitch.conf already exists,
/usr/share/factory/etc/nsswitch.conf file is not installed in /etc
directory since etc.conf uses 'C' as the type of tmpfiles.d
configuration so this patch does not make any error in network
operation.

Change-Id: I1c4ea8dcdaae002d5cfc3db4be53470c8d2169ca
Signed-off-by: Sangjung Woo <sangjung.woo@samsung.com>