[ARM] unconditionally define __virt_to_phys and __phys_to_virt

There is no machine class overriding this.  If non linear translations
are implemented again for some machines then this could be restored at
that time.
Signed-off-by: NNicolas Pitre <nico@marvell.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/memory.h

@@ -112,10 +112,8 @@
  * private definitions which should NOT be used outside memory.h
  * files.  Use virt_to_phys/phys_to_virt/__pa/__va instead.
  */
-#ifndef __virt_to_phys
 #define __virt_to_phys(x)	((x) - PAGE_OFFSET + PHYS_OFFSET)
 #define __phys_to_virt(x)	((x) - PHYS_OFFSET + PAGE_OFFSET)
-#endif
 
 /*
  * Convert a physical address to a Page Frame Number and back