Update to oc_api: interrupt handler definition
Update to oc_api: interrupt handler definition

* Modified the pattern for defining "interrupt handlers" in tiny OCF
  applications leading now to a more desirable function like style.

Change-Id: Ic9350a536bbf9f355687136a093316663858cc78
Signed-off-by: Kishen Maloor <c62ddea3cd661a9268bff15f07fc2229cdc9ac02@intel.com>
Signed-off-by: Thiago Macieira <0ed1648d92ca0373297a182b1dba1b974ad10d88@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/10421

iotivity/iotivity-constrained,iotivity/iotivity-constrained,iotivity/iotivity-constrained,iotivity/iotivity-constrained