staging: ozwpan: Separate success & failure case for oz_hcd_pd_arrived()

staging: ozwpan: Separate success & failure case for oz_hcd_pd_arrived()

This patch separates success & failure block along with fixing
following issues:-

1. The way oz_hcd_pd_arrived() looks now it's easy to think we free "ep" but
actually we do this spaghetti thing of setting it to NULL on success.

2. It is hard to read it because there are unlocks scattered throughout.

3. Currently we set "ep" to NULL on the success path and then test it and or
free it. In current code you have to scroll to the start of the function
to read code.

Original patch was submitted by Dan here :-
http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel/2013-August/040113.html

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Rupesh Gujare <rupesh.gujare@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>