[ARM] 3259/1: remove phys_ram from struct machine_desc (part 1)

Patch from Nicolas Pitre

This field is redundent since it must be equal to PHYS_OFFSET anyway.

First, let's  use PHYS_OFFSET directly instead.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>