The NAND IP needs 3 clocks(nand_x_clk, nand_clk, and nand_ecc_clk). This
patch adds a nand_clk, which is derived from the nand_x_clk, but has a
fixed divider of 4, and the nand_ecc_clk, which is derived from the
nand_x_clk.

Update the NAND node to use the additional clocks.
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>
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v2: add nand_ecc_clk and update commit message