Changeset e706a9d in rtems

arm/raspberrypi: ensure that RTEMS application image can be started by U-boot.

The current versions of U-boot start kernel/RTEMS application image
with instruction and data caches enabled and it sets exception
base register to new address after its self-relocation.

ldr r0, [r9, #GD_RELOCADDR] /* r0 = gd->relocaddr */
mcr p15, 0, r0, c12, c0, 0 /* Set VBAR */

Included changes in bsp_start_hook_0 restore default state to
allow RTEMS image to run after startup from newer U-boot version
on Raspberry Pi.

Clear interrupt enable registers in interrupt controller
to ensure that RTEMS starts from well defined state.