Fix TC2 kernel config variables

The TC2 kernel config variables were wrong after a recent update to the
build scripts.

For example, the mobile_bb zImage was used for all variants, such as
Android or OE, leaving the system unbootable.

Change-Id: Ibf40cc0fbb03474e5a606c2256b73eaf1a8df7bc
Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>