wificond_service: drop system_service typeattribute

wificond_service is not a system_server service, so drop the
typeattribute.

Provide find permission for system_server so it can still call
wificond.

Test: compile and run on emulator. Also check built policy to verify
the permissions changes are as expected. system_server should have lost
the add permissions on wificond_service. Most importantly this needs
to be tested on a device with wificond.

Change-Id: I6dd655a5ac1dbfef809b8759a86429557a7c1207
Signed-off-by: William Roberts <william.c.roberts@intel.com>