docs(psci): drop outdated cache maintenance comment

The comment was written when cache maintenance had to be considered when
calling this function. But that argument was dropped a while back and
this comment no longer makes any sense.

Change-Id: Ib68293f23cc3edca3010164dfe8866956b8e1a63
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
1 file changed