udev: avoid udev stopping persistent pppd connections
udev: avoid udev stopping persistent pppd connections

When a pppd session is disconnected it triggers the udev to ifdown the
ppp link which kills pppd and inhibits a reconnection.

Now avoid udev stopping ppp connections.

See also:
 https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/396804
 https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/78043
 http://ubuntuforums.org/showthread.php?t=1177021
 http://rants.atmurray.net/2007/01/pppd-persist-not-so-persist-with-udev.html

Signed-off-by: Mario Schuknecht <35684c95a1a560447336c8e16b47e9265798f028@dresearch-fe.de>
Acked-by: Steffen Sledz <2e29ea0aa1503a723683d9a206c59d4c02f6bad0@dresearch-fe.de>

rascalmicro/openembedded-rascal,rascalmicro/openembedded-rascal,rascalmicro/openembedded-rascal,rascalmicro/openembedded-rascal,rascalmicro/openembedded-rascal,rascalmicro/openembedded-rascal,rascalmicro/openembedded-rascal,rascalmicro/openembedded-rascal