ntp: cleanup recipes and fix SSL support

* Move common definitions to the inc file
* Drop override of do_configure which doesn't seem to be needed anymore
* Fold ntp-ssl into the ntp recipe as a PACKAGECONFIG option for those
  who want it (default to off) and fix configure-time checks to detect
  OpenSSL properly so that it gets enabled when selected
* Remove ntp-bin package and put its contents in currently empty
  ntp-utils package (with migration path)
* Fix hardcoded paths in ntpd initscript
* Specify ntpd.conf as a configuration file for packaging purposes
* Rearrange so that packaging definitions are towards the end in the
  expected order
* Delete unused "ntp" initscript file
* Add SUMMARY
* Update HOMEPAGE

This reapplies some of the changes from the original patch by
Morgan Little <morgan.little@windriver.com>.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>