consolidate io_remap_pfn_range definitions

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/c6x/include/asm/pgtable.h

@@ -71,7 +71,6 @@ extern unsigned long empty_zero_page;
  * No page table caches to initialise
  */
 #define pgtable_cache_init()   do { } while (0)
-#define io_remap_pfn_range      remap_pfn_range
 
 #include <asm-generic/pgtable.h>