ARM: 7204/1: arch/arm/kernel/setup.c: initialize arm_dma_zone_size earlier

arm_dma_zone_size is used by arm_bootmem_free() which is called by
paging_init(). Thus it needs to be set before calling it.

Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: stable@kernel.org
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>