powerpc/fsl-booke: Fix CONFIG_RELOCATABLE support on FSL Book-E ppc32

The following commit broke CONFIG_RELOCATABLE support on FSL Book-E
parts:

commit 549e8152
Author: Paul Mackerras <paulus@samba.org>
Date:   Sat Aug 30 11:43:47 2008 +1000

    powerpc: Make the 64-bit kernel as a position-independent executable

The change to __va and __pa to use PAGE_OFFSET & MEMORY_START causes
problems on the Book-E parts because we don't know MEMORY_START until
after we parse the device tree.  We need __va to work properly to even
parse the device tree so we have a chicken an egg.  So go back to using
he other definition of __va/__pa on CONFIG_BOOKE and use the
PAGE_OFFSET/MEMORY_START version on "Classic" PPC64.

Also updated casts to handle phys_addr_t being a different size from
unsigned long (ie 36-bit physical on PPC32).
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/include/asm/page.h

@@ -108,8 +108,21 @@ extern phys_addr_t kernstart_addr;
 #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
 #define virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
 
-#define __va(x) ((void *)((unsigned long)(x) + PAGE_OFFSET - MEMORY_START))
+/*
+ * On Book-E parts we need __va to parse the device tree and we can't
+ * determine MEMORY_START until then.  However we can determine PHYSICAL_START
+ * from information at hand (program counter, TLB lookup).
+ *
+ * On non-Book-E PPC64 PAGE_OFFSET and MEMORY_START are constants so use
+ * the other definitions for __va & __pa.
+ */
+#ifdef CONFIG_BOOKE
+#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) - PHYSICAL_START + KERNELBASE))
+#define __pa(x) ((unsigned long)(x) + PHYSICAL_START - KERNELBASE)
+#else
+#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) + PAGE_OFFSET - MEMORY_START))
 #define __pa(x) ((unsigned long)(x) - PAGE_OFFSET + MEMORY_START)
+#endif
 
 /*
  * Unfortunately the PLT is in the BSS in the PPC32 ELF ABI,