of: remove special case definition of of_read_ulong()

Special case of of_read_ulong() was defined for PPC32 to toss away
all but the last 32 bits when a large number value was read, and the
'normal' version for ppc64 just #defined of_read_ulong to of_read_number
which causes compiler warnings on MicroBlaze and other 32 bit
architectures because it returns a u64 instead of a ulong.

This patch fixes the problem by defining a common implementation of
of_read_ulong() that works everywhere.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>
Tested-by: Michal Simek <monstr@monstr.eu>

include/linux/of.h

@@ -113,14 +113,11 @@ static inline u64 of_read_number(const u32 *cell, int size)
 }
 
 /* Like of_read_number, but we want an unsigned long result */
-#ifdef CONFIG_PPC32
 static inline unsigned long of_read_ulong(const u32 *cell, int size)
 {
-	return cell[size-1];
+	/* toss away upper bits if unsigned long is smaller than u64 */
+	return of_read_number(cell, size);
 }
-#else
-#define of_read_ulong(cell, size)	of_read_number(cell, size)
-#endif
 
 #include <asm/prom.h>