util: remove flash_cr50.py
util: remove flash_cr50.py

flash_cr50 is maintained in platform/cr50. Remove the copy from the EC.

BUG=b:205330772
BRANCH=none
TEST=none

Change-Id: I394ce714c467d3177c3da2cb903b106d952ba8f9
Signed-off-by: Mary Ruthven <81380f3403fed74252e92df3ed012a1819ec6296@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3265230
Reviewed-by: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>
Commit-Queue: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec