With the new i.mx clock framework the mxc_nand clock is registered as:

clk_register_clkdev(clk[nfc_gate], NULL, "mxc_nand");0")

So we do not need to pass "nfc" string and can use NULL instead.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>