zephyr: use printk instead of shell_
zephyr: use printk instead of shell_

The shell print function is not as complete as the printk function. I
see have to add functionality for the printk version, but the shell
version does not support the specifiers we use in gettime console (e.g.
"0x%016llx -> %11.6lld" format specifier)

BRANCH=none
BUG=none
TEST=flash volteer and call gettime on console and see correct results

Signed-off-by: Jett Rink <9d4aef0593e6843318d99df31597fb6153b89787@chromium.org>
Change-Id: Iadf9fc05708c31b70735145ed43750c308b07f39
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2446028

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