tools: arm64: Grab a copy of esr.h from kernel

Grab esr.h and brk-imm.h for subsequent use in KVM selftests.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241025203106.3529261-3-oliver.upton@linux.dev


Signed-off-by: Oliver Upton <oliver.upton@linux.dev>