sh: pci memory range checking code

This patch changes the code to use __is_pci_memory() instead of
is_pci_memaddr(). __is_pci_memory() loops through all the pci
channels on the system to match memory windows.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>