clk: mvebu: Support Armada 380 SoC on the core divider clock

This commit adds support for the Core Divider clocks of the Armada
380 SoCs. Similarly to Armada 370 and XP, the Core Divider clocks of
the 380 have gate capabilities. The only difference is the register layout.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Link: https://lkml.kernel.org/r/1394742273-5113-2-git-send-email-ezequiel.garcia@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>