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>
diff --git a/arch/arm/mach-tegra/pcie.c b/arch/arm/mach-tegra/pcie.c
index 2941212..031cd0a 100644
--- a/arch/arm/mach-tegra/pcie.c
+++ b/arch/arm/mach-tegra/pcie.c
@@ -912,6 +912,8 @@
 	if (!(init_port0 || init_port1))
 		return -ENODEV;
 
+	pcibios_min_mem = 0;
+
 	err = tegra_pcie_get_resources();
 	if (err)
 		return err;