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/mach-ixp4xx/common-pci.c

@@ -346,6 +346,11 @@ void __init ixp4xx_pci_preinit(void)
 {
 	unsigned long cpuid = read_cpuid_id();
 
+#ifdef CONFIG_IXP4XX_INDIRECT_PCI
+	pcibios_min_mem = 0x10000000; /* 1 GB of indirect PCI MMIO space */
+#else
+	pcibios_min_mem = 0x48000000; /* 64 MB of PCI MMIO space */
+#endif
 	/*
 	 * Determine which PCI read method to use.
 	 * Rev 0 IXP425 requires workaround.