wpa-supplicant: fix breakage during rebuild

wpa-supplicant: fix breakage during rebuild

Install phase currently edits files in $S with sed. This causes breakage
if install is run a second time (due to sstate hash rebuild for example)

The result is hidden build breakage, in particular
/usr/share/dbus-1/system-services/fi.w1.wpa_supplicant1.service now contains:

Exec=/usr/usr/sbin/wpa_supplicant -u

rather than:

Exec=/usr/sbin/wpa_supplicant -u

This patch does the sed edit after the files are copied to $D, which should be safe.

Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>