gps: replace redundant lambda wrapper with method value
gps: replace redundant lambda wrapper with method value

Originally submitted by Iskander Sharipov, who has signed the CLA, as
https://github.com/golang/dep/pull/2029; submitting under my name to
get past the CLA bot.

Signed-off-by: Iskander Sharipov <c44937ca97a307fe72537e11296835ddc74e116a@gmail.com>

golang/dep,golang/dep,golang/dep