sparc64: Fix range check in kern_addr_valid().

In commit b2d43834 ("sparc64: Make
PAGE_OFFSET variable."), the MAX_PHYS_ADDRESS_BITS value was increased
(to 47).

This constant reference to '41UL' was missed.
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/include/asm/pgtable_64.h

@@ -916,7 +916,7 @@ static inline bool kern_addr_valid(unsigned long addr)
 {
 	unsigned long paddr = __pa(addr);
 
-	if ((paddr >> 41UL) != 0UL)
+	if ((paddr >> MAX_PHYS_ADDRESS_BITS) != 0UL)
 		return false;
 	return test_bit(paddr >> 22, sparc64_valid_addr_bitmap);
 }