docs: Fix typo in Documentation/arm/marvell.rst

Fix typo in the documentation, changed from 'comatible' to
'compatible.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Link: https://lore.kernel.org/r/20210531134235.720351-1-iwamatsu@nigauri.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>