consolidate io_remap_pfn_range definitions

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

arch/um/include/asm/pgtable.h

@@ -69,8 +69,6 @@ extern unsigned long end_iomem;
 #define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY | _PAGE_ACCESSED)
 #define PAGE_KERNEL_EXEC	__pgprot(__PAGE_KERNEL_EXEC)
 
-#define io_remap_pfn_range	remap_pfn_range
-
 /*
  * The i386 can't do page protection for execute, and considers that the same
  * are read.