make: Add check for flash support
make: Add check for flash support

BRANCH=none
BUG=none
TEST=make buildall -j
TEST=make BOARD=hatch flash
     # Should emit error that board isn't supported
TEST=make BOARD=nucleo-f072rb flash
     # Should start openocd or error that command not found

Signed-off-by: Craig Hesling <383db090fd8ef907a606ac8a9eccd2962bc489cf@chromium.org>
Change-Id: Id13847d51392cc098ff7b289d120978202019aaf
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1952198
Reviewed-by: Daisuke Nojiri <fd5f93af191bf7e8f73ea71cc3c0f66b41b1dd49@chromium.org>
Reviewed-by: Jett Rink <9d4aef0593e6843318d99df31597fb6153b89787@chromium.org>
Reviewed-by: Aseda Aboagye <12c9b286316a940fd31c24070da5ab64cdd4d0e7@chromium.org>

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