clk: sprd: add mipi_csi_xx gate clocks

mipi_csi_xx clocks are used by camera sensors.

Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Link: https://lkml.kernel.org/r/20200527053638.31439-5-zhang.lyra@gmail.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>