fdtdump: fix -Werror=int-to-pointer-cast

With mingw64-gcc, the compiler complains with various warnings:
error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210825121350.213551-1-marcandre.lureau@redhat.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

fdtdump.c

@@ -21,7 +21,7 @@
 #define MAX_VERSION 17U
 
 #define ALIGN(x, a)	(((x) + ((a) - 1)) & ~((a) - 1))
-#define PALIGN(p, a)	((void *)(ALIGN((unsigned long)(p), (a))))
+#define PALIGN(p, a)	((void *)(ALIGN((uintptr_t)(p), (a))))
 #define GET_CELL(p)	(p += 4, *((const fdt32_t *)(p-4)))
 
 static const char *tagname(uint32_t tag)