ARM: 9435/1: ARM/nommu: Fix typo "absence"

There is a spelling mistake of 'absense' in comments which
should be 'absence'.

Link: https://lore.kernel.org/all/[e-mail]/
Signed-off-by: WangYuli <[e-mail]>
Reviewed-by: Vladimir Murzin <[e-mail]>
Signed-off-by: Russell King (Oracle) <[e-mail]>

arch/arm/mm/dma-mapping-nommu.c

···
 		/*
 		 * Cache support for v7m is optional, so can be treated as
 		 * coherent if no cache has been detected. Note that it is not
-		 * enough to check if MPU is in use or not since in absense of
+		 * enough to check if MPU is in use or not since in absence of
 		 * MPU system memory map is used.
 		 */
 		dev->dma_coherent = cacheid ? coherent : true;