tegra: Use SPDX license identifier
tegra: Use SPDX license identifier

Change-Id: I770b2db68c8d115d10067bb557e32b5e269c94a5
Signed-off-by: Antonio Nino Diaz <5c24ff39be768bf31f4deee44042a11772cfd02a@arm.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware