clk: hi3660: Set PPLL2 to 2880M

Set PPLL2 to 2880M. With this patch, we saw better compatibility
on various 1080p HDMI monitors.

Signed-off-by: Zhong Kaihua <zhongkaihua@huawei.com>
Signed-off-by: Zheng Shaobo <zhengshaobo1@huawei.com>
Acked-by: Zhangfei Gao <zhangfei.gao@linaro.org>
[sboyd@codeaurora.org: Add UL to long number to silence C90
warning]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>