powerpc: mark 64-bit PD_HUGE constant as unsigned long

When compiled for 64-bit, the PD_HUGE constant is a 64-bit integer.
Mark it as an unsigned long.

This squashes over a thousand sparse warnings on my minimal T4240RDB
(e6500, ppc64be) config, of the following 2 forms:

arch/powerpc/include/asm/hugetlb.h:52:49: warning: constant 0x8000000000000000 is so big it is unsigned long
arch/powerpc/include/asm/nohash/pgtable.h:269:49: warning: constant 0x8000000000000000 is so big it is unsigned long
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/page.h

@@ -289,7 +289,7 @@ static inline bool pfn_valid(unsigned long pfn)
  * page tables at arbitrary addresses, this breaks and will have to change.
  */
 #ifdef CONFIG_PPC64
-#define PD_HUGE 0x8000000000000000
+#define PD_HUGE 0x8000000000000000UL
 #else
 #define PD_HUGE 0x80000000
 #endif