tpm: allow 0 as valid i2c bus number

tpm driver uses bus=0 as indication of uninitialized tpm device. this
change allows 0 as a valid i2c bus number.

BUG=None
BRANCH=ToT
TEST=Built cosmos.

Change-Id: Iac55e88db4ef757a292270e7201d8fdd37a90b50
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/226294
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
1 file changed