xen/x86: free_p2m_page: use memblock_free_ptr() to free a virtual pointer

free_p2m_page() wrongly passes a virtual pointer to memblock_free() that
treats it as a physical address.

Call memblock_free_ptr() instead that gets a virtual address to free the
memory.

Link: https://lkml.kernel.org/r/20210930185031.18648-3-rppt@kernel.orgSigned-off-by: NMike Rapoport <rppt@linux.ibm.com>
Reviewed-by: NJuergen Gross <jgross@suse.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Shahab Vahedi <Shahab.Vahedi@synopsys.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/x86/xen/p2m.c

@@ -197,7 +197,7 @@ static void * __ref alloc_p2m_page(void)
 static void __ref free_p2m_page(void *p)
 {
 	if (unlikely(!slab_is_available())) {
-		memblock_free((unsigned long)p, PAGE_SIZE);
+		memblock_free_ptr(p, PAGE_SIZE);
 		return;
 	}