microblaze: Enable PCI, missing files

There are two parts of changes. The first is just enable
PCI in Makefiles and in Kconfig. The second is the rest of
missing files. I didn't want to add it with previous patch
because that patch is too big.

Current Microblaze toolchain has problem with weak symbols
that's why is necessary to apply this changes to be possible
to compile pci support.
Xilinx knows about this problem.

Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/include/asm/io.h

@@ -17,7 +17,21 @@
 #include <linux/mm.h>          /* Get struct page {...} */
 #include <asm-generic/iomap.h>
 
-#define PCI_DRAM_OFFSET 0
+#ifndef CONFIG_PCI
+#define _IO_BASE	0
+#define _ISA_MEM_BASE	0
+#define PCI_DRAM_OFFSET	0
+#else
+#define _IO_BASE	isa_io_base
+#define _ISA_MEM_BASE	isa_mem_base
+#define PCI_DRAM_OFFSET	pci_dram_offset
+#endif
+
+extern unsigned long isa_io_base;
+extern unsigned long pci_io_base;
+extern unsigned long pci_dram_offset;
+
+extern resource_size_t isa_mem_base;
 
 #define IO_SPACE_LIMIT (0xFFFFFFFF)