UPSTREAM: USB: option: clean up probe coding style

UPSTREAM: USB: option: clean up probe coding style

Clean up option probe by introducing intermediate variables and fixing
up comments.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 378fac2a46decbcd16b42044303ba8a1a3f8001e)

Change-Id: I0ba9fbbabc05f314742cbdb58d231f5e12dc45c7
Signed-off-by: Ben Chan <benchan@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/50561
Reviewed-by: Olof Johansson <olofj@chromium.org>