Some '= 0' -> '= NULL' cleanup for pointer fields and return values.
Some '= 0' -> '= NULL' cleanup for pointer fields and return values.

From Brad.

Tested by nick@ just to be sure.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars