scripts: update_gpu_drivers: Using kevin and elm to build prebuilts

I doubt that many devs still have gru and oak boards setup on their
workstations, let's switch to building the prebuilts using kevin
and elm.

BUG=none
TEST=./update_gpu_drivers.sh --package img-ddk

Change-Id: Iea2839f03ad78aa6d75b938667ae6d112dc1388b
Reviewed-on: https://chromium-review.googlesource.com/906052
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Stephen Barber <smbarber@chromium.org>
diff --git a/update_gpu_drivers.sh b/update_gpu_drivers.sh
index ff1b731..670d1e6 100755
--- a/update_gpu_drivers.sh
+++ b/update_gpu_drivers.sh
@@ -31,13 +31,13 @@
 
 PARAMS_mali_drivers=(
   "daisy daisy daisy overlay-daisy"
-  "gru gru gru baseboard-gru"
+  "kevin gru gru baseboard-gru"
   "peach_pit peach peach overlay-peach"
   "veyron_jerry veyron veyron overlay-veyron"
 )
 
 PARAMS_img_ddk=(
-  "oak oak oak chipset-mt8173"
+  "elm oak oak chipset-mt8173"
 )
 
 # Script must run inside the chroot