Fixed bug IOT-798

Fixed bug IOT-798

IsRequestWithinValidTime in iotvticalendar.c was only checking for the
valid date when recurrence was NULL. Update the IsRequestWithinValidTime
function to check for both valid date and time.

Change-Id: Ifec7520f07958fd7ded36c017c0b08acd3053ff0
Signed-off-by: Shilpa Sodani <shilpa.a.sodani@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/3881
Reviewed-by: Mark Tung <mark.y.tung@intel.com>
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Sachin Agrawal <sachin.agrawal@intel.com>