.gitignore: ignore GKI generated defconfigs

ignore lahaina-qgki-consolidate_defconfig file generated
by GKI scripts as this file auto-generated at build time.

Change-Id: I3edbbbf90b581642da81993a49fdc5264a4324a3
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>