The Generic Timer is an optional extension to an ARMv7-A implementation.
The generic delay timer can be used from any architecture supported by
the Trusted Firmware. In ARMv7 it is needed to check that this feature
is present. In ARMv8 it is always present.

Change-Id: Ib7e8ec13ffbb2f64445d4ee48ed00f26e34b79b7
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>