clk: socfpga: agilex: mpu_l2ram_clk should be mpu_ccu_clk

Preliminary documentation documented the mpu_l2ram_clk, but since then,
the mpu_l2ram_clk is no longer documented. It's now referred to as
mpu_ccu_clk.

Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
Link: https://lore.kernel.org/r/20200616202417.14376-3-dinguyen@kernel.org


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