Fix u-boot compilation warnings.

U-boot compiler frowns at C++ style comments and escaped lines in
the end of the file, causing u-boot compilation warnings, which
go unnoticed and bury more serious problems in the compiler
output.

This change modifies the config files to make tegra2 u-boot
compile cleanly.

BUG=chromium-os:16410
TEST=manual:

This test requires the corresponding change in the
chromeos-u-boot tree. Run the following commands:

 emerge-tegra2_kaen --unmerge chromeos-u-boot-config
 emerge-tegra2_kaen u-boot-config
 emerge-tegra2_kaen chromeos-u-boot

Observe clean compilation.

Change-Id: I9144093238e7f86b2c4e35ea6d49a10d59c4ad69
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: http://gerrit.chromium.org/gerrit/2463
Reviewed-by: Tom Warren <twarren@nvidia.com>
19 files changed