Remove uneeded code from pkg-map

This patch removes a couple of lines of redundant code.  In Python,
the get method on a dictionary defaults the return value to None,
so the method never raises a key error.

https://docs.python.org/2/library/stdtypes.html#typesmapping

Change-Id: I180877f9be23d373cd63771bb3682d6587ec6fac
Merge "Remove uneeded code from pkg-map"