ARM: integrator: use devm_ioremap() to remap CM

In the PCIv3 driver, use devm_ioremap() instead of just ioremap()
when remapping the system controller in the PCIv3 driver, so
the mapping will be automatically released on probe failure.

Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>