grunt: Disable CONFIG_BRINGUP option
grunt: Disable CONFIG_BRINGUP option

Bringup went well so this this option is no longer needed.

BUG=None
TEST=Build & boot
BRANCH=None

Change-Id: I415161ab77d2a6b1ce59d6773d3cf78176cd1e96
Signed-off-by: Martin Roth <79230511ccf79da3f7e9e82dbcc9c1ec2f734fa0@google.com>
Reviewed-on: https://chromium-review.googlesource.com/882182
Commit-Ready: Martin Roth <79230511ccf79da3f7e9e82dbcc9c1ec2f734fa0@chromium.org>
Tested-by: Martin Roth <79230511ccf79da3f7e9e82dbcc9c1ec2f734fa0@chromium.org>
Reviewed-by: Justin TerAvest <f2d83486a72e2fb2fbfb163be787ddf5d8d3393e@chromium.org>

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