powerpc/mm: drop ppc_md.iounmap() and __iounmap()

ppc_md.iounmap() is never set, drop it.

Once ppc_md.iounmap() is gone, iounmap() remains the only user of
__iounmap() and iounmap() does nothing else than calling __iounmap().
So drop iounmap() and make __iounmap() the new iounmap().

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d73ba92bb7a387cc58cc34666d7f5158a45851b0.1566309262.git.christophe.leroy@c-s.fr

arch/powerpc/mm/pgtable_64.c

@@ -266,7 +266,7 @@ void __iomem * ioremap_prot(phys_addr_t addr, unsigned long size,
  * Unmap an IO region and remove it from imalloc'd list.
  * Access to IO memory should be serialized by driver.
  */
-void __iounmap(volatile void __iomem *token)
+void iounmap(volatile void __iomem *token)
 {
 	void *addr;
 
@@ -283,21 +283,12 @@ void __iounmap(volatile void __iomem *token)
 	vunmap(addr);
 }
 
-void iounmap(volatile void __iomem *token)
-{
-	if (ppc_md.iounmap)
-		ppc_md.iounmap(token);
-	else
-		__iounmap(token);
-}
-
 EXPORT_SYMBOL(ioremap);
 EXPORT_SYMBOL(ioremap_wc);
 EXPORT_SYMBOL(ioremap_prot);
 EXPORT_SYMBOL(__ioremap);
 EXPORT_SYMBOL(__ioremap_at);
 EXPORT_SYMBOL(iounmap);
-EXPORT_SYMBOL(__iounmap);
 EXPORT_SYMBOL(__iounmap_at);
 
 #ifndef __PAGETABLE_PUD_FOLDED