clk: kirkwood: Add support for MV98DX1135

The 98DX1135 is a switch chip with an integrated CPU. This is similar to
the 98DX4122 except that the core clock speed is fixed to 166Mhz.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>