ARM: Fix .size directive for xscale_dma_a0_map_area

gas used to accept (and ignore?) .size directives which referred to
undefined symbols, as this does.  In binutils 2.21 these are treated
as fatal errors.
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Signed-off-by: NEric Miao <eric.y.miao@gmail.com>

arch/arm/mm/proc-xscale.S

@@ -395,7 +395,7 @@ ENTRY(xscale_dma_a0_map_area)
 	teq	r2, #DMA_TO_DEVICE
 	beq	xscale_dma_clean_range
 	b	xscale_dma_flush_range
-ENDPROC(xscsale_dma_a0_map_area)
+ENDPROC(xscale_dma_a0_map_area)
 
 /*
  *	dma_unmap_area(start, size, dir)