KConfig: Vexpress: build the ARM_GLOBAL_TIMER with vexpress platform
KConfig: Vexpress: build the ARM_GLOBAL_TIMER with vexpress platform

The Cortex A5 now contains bindings for the global timer
driver. Ensure that the driver is built with a vexpress platform.

Signed-off-by: Matthew Leach <968f99dd328b703d57aa48028082f52162903fed@arm.com>
Signed-off-by: Daniel Lezcano <e9fa45941f2ebe89c1b9d6c5f339ab42eadb8567@linaro.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs