The TBBR documentation has been written along with an early
implementation of the code. At that time, the range of supported
encryption and hash algorithms was failry limited. Since then, support
for other algorithms has been added in TF-A but the documentation has
not been updated.

Instead of listing them all, which would clutter this document while
still leaving it at risk of going stale in the future, remove specific
references to the original algorithms and point the reader at the
relevant comprehensive document for further details.

Change-Id: I29dc50bc1d53b728091a1fbaa1c3970fb999f7d5
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>