cortex-m0: Fix panic reason on div0
cortex-m0: Fix panic reason on div0

The wrong constant was used in the previous commit.

BUG=chrome-os-partner:36744
TEST=None
BRANCH=Samus

Signed-off-by: Shawn Nematbakhsh <5259333ce42e3ace6a73988cec7115ed9d3a661a@chromium.org>
Change-Id: I74e365b00adb6909a4940229647f9aecebe5e0b1
Reviewed-on: https://chromium-review.googlesource.com/250700
Reviewed-by: Vic Yang <5fd92abeee651458f98e2856f4f200ee971cee4d@chromium.org>
Reviewed-by: Alec Berg <1a4429eeda29095a12e19a73405f80f5b7f37a63@chromium.org>

md5555/ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,fourier49/BIZ_EC,eatbyte/chromium-ec,fourier49/BIZ_EC,md5555/ec,md5555/ec,coreboot/chrome-ec,fourier49/BZ_DEV_EC,fourier49/BIZ_EC,akappy7/ChromeOS_EC_LED_Diagnostics,eatbyte/chromium-ec,coreboot/chrome-ec,eatbyte/chromium-ec,coreboot/chrome-ec,fourier49/BZ_DEV_EC,fourier49/BZ_DEV_EC,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,fourier49/BZ_DEV_EC,akappy7/ChromeOS_EC_LED_Diagnostics,fourier49/BIZ_EC,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,md5555/ec,eatbyte/chromium-ec