ARM: convert PCI defines to variables

Convert PCIBIOS_MIN_IO and PCIBIOS_MIN_MEM to variables to allow
multi-platform builds. This also removes the requirement for a platform to
have a mach/hardware.h.

The default values for i/o and mem are 0x1000 and 0x01000000, respectively.
Per Arnd Bergmann, other values are likely to be incorrect, but this commit
does not try to address that issue.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/plat-iop/pci.c

@@ -374,6 +374,9 @@ void __init iop3xx_pci_preinit_cond(void)
 
 void __init iop3xx_pci_preinit(void)
 {
+	pcibios_min_io = 0;
+	pcibios_min_mem = 0;
+
 	iop3xx_atu_disable();
 	iop3xx_atu_setup();
 	iop3xx_atu_debug();