pc-bios: s390x: Make u32 ptr check explicit

Let's make it a bit more clear that we check the full 64 bits to fit
into the 32 we return.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20200624075226.92728-11-frankja@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

pc-bios/s390-ccw/helper.h

@@ -19,7 +19,7 @@
 /* Avoids compiler warnings when casting a pointer to a u32 */
 static inline uint32_t ptr2u32(void *ptr)
 {
-    IPL_assert((uint64_t)ptr <= 0xffffffff, "ptr2u32: ptr too large");
+    IPL_assert((uint64_t)ptr <= 0xffffffffull, "ptr2u32: ptr too large");
     return (uint32_t)(uint64_t)ptr;
 }