arm-trusted-firmware: new package

arm-trusted-firmware: new package

Signed-off-by: Joao Pinto <jpinto@synopsys.com>
[Thomas:
 - Rename the package from atfirmware to arm-trusted-firmware, in order
   to match upstream.
 - Remove option to apply custom patches. We no longer add such options,
   and use the global patch directory instead.
 - Rename the repo URL/version options, in order to not be Git specific,
   in case support for fetching from other VCS is added later. This is
   consistent with how other bootloaders handle this.
 - Add license information.
 - Do not add a weird dependency on the vexpress-firmware package in
   Config.in. Instead, simply use it if it's available. Of course, some
   configurations (such as the juno configuration) will fail to build if
   vexpress-image is not enabled, but it's the responsibility of the
   user to create a config that builds.
 - Simplify misc aspects in the .mk file.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>