pujjoga: switch to using npcx-40mhz snippet

De-duplicate code switching the npcx-40mhz snippet

BUG=none
TEST=zmake compare-builds pujjoga

Change-Id: I6c682a70f03728fa57a25adc59f912e60a87a09c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/7843235
Tested-by: Keith Short <keithshort@chromium.org>
Reviewed-by: Jeremy Bettis <jbettis@chromium.org>
Commit-Queue: Keith Short <keithshort@chromium.org>
Reviewed-by: Eric Yilun Lin <yllin@google.com>
Code-Coverage: Zoss <zoss-cl-coverage@prod.google.com>