tc: added support for building android with GPU prebuilt

This change includes building Android with GPU prebuilt.
GPU will not be built from source, instead prebuilt bin and lib
will be used if TC_GPU is set to `hwr-prebuilt`.

Signed-off-by: Rupinderjit Singh <rupinderjit.singh@arm.com>
Signed-off-by: Ahmed Genidi <Ahmed.Genidi@arm.com>