write_firmware: switch from nvflash to tegrarcm
write_firmware: switch from nvflash to tegrarcm

tegrarcm is an open source replacement to nvflash for writing firmware
to tegra devices.

BUG=None
TEST=emerged and flashed tegra2_seaboard with "cros_bundle_firmware -w
usb -F spi"
CQ-DEPEND=I8b998b04065846293e4c100f00db9c6ed6fe4e54

Change-Id: I1792836fd45aa9566536674c9e2c801e7843938c
Reviewed-on: https://gerrit.chromium.org/gerrit/25846
Tested-by: Allen Martin <26c037b3f0ea082472e5dda5744e35dcf1dcb620@nvidia.com>
Reviewed-by: Rhyland Klein <9c6f026f68ffecc44f215af186ef513cd72b6ce4@nvidia.com>
Reviewed-by: Simon Glass <c00b0378376498bd9cd974c388df8854c0131d27@chromium.org>
Commit-Ready: Allen Martin <26c037b3f0ea082472e5dda5744e35dcf1dcb620@nvidia.com>

mgireesh05/dev-util,coreos/dev-util,mgireesh05/dev-util,coreos/dev-util,mgireesh05/dev-util,marineam/coreos-dev-util,marineam/coreos-dev-util,coreos/dev-util