connman: Remove connman.service file

The modifications in connman.service file are not needed anymore as the extra
cases that were being handled by our service file are now handled in connman
sources.

JIRA: http://jira.alm.mentorg.com:8080/browse/SB-3096

Signed-off-by: Fahad Usman <fahad_usman@mentor.com>
Merge pull request #238 from fahadusman/remove-connman-service-file

connman: Remove connman.service file