P2PS: Fix PD Request parameter handling

P2PS: Fix PD Request parameter handling

In P2PS PD Request processing in some error case scenarios, such as
verification of the WPS config method, the flow aborts before saving
mandatory P2PS PD Request attributes. This in turn causes the control
interface notification events to be sent with invalid parameters.

Fix this by changing the order of verification and processing steps of
the PD Request message handling.

Signed-off-by: Max Stepanov <Max.Stepanov@intel.com>