ARM: clps711x: Using a single definition for the PHYS and VIRT registers offset

Using a single definition for the physical and virtual address register for all
variants boards clps711x. This patch also includes the use of a single function
clps_read/write in some units.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>