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/fca25741-c89f-43ea-95af-5e3232d513fc@arm.com/


Signed-off-by: WangYuli <wangyuli@uniontech.com>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>