buildroot

arm-trusted-firmware: bump to version 1.4

The license file got reformatted as reStructuredText, but the license itself
didn't change.

Drop unneeded md5sum and add license hash.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>