ARM: PCI: versatile: Fix SMAP register offsets

The SMAP register offsets in the versatile PCI controller code were
all off by four.  (This didn't have any observable bad effects
because on this board PHYS_OFFSET is zero, and (a) writing zero to
the flags register at offset 0x10 has no effect and (b) the reset
value of the SMAP register is zero anyway, so failing to write SMAP2
didn't matter.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Cc: stable@vger.kernel.org
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kevin Hilman <khilman@linaro.org>