mtd: rawnand: arasan: Fix clock rate in NV-DDR

According to the Arasan NAND controller spec, the flash clock rate for SDR
must be <= 100 MHz, while for NV-DDR it must be the same as the rate of the
CLK line for the mode. The driver previously always set 100 MHz for NV-DDR,
which would result in incorrect behavior for NV-DDR modes 0-4.

The appropriate clock rate can be calculated from the NV-DDR timing
parameters as 1/tCK, or for rates measured in picoseconds,
10^12 / nand_nvddr_timings->tCK_min.

Fixes: 197b88fe ("mtd: rawnand: arasan: Add new Arasan NAND controller")
CC: stable@vger.kernel.org # 5.8+
Signed-off-by: Olga Kitaina <okitain@gmail.com>
Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@xilinx.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220628154824.12222-3-amit.kumar-mahapatra@xilinx.com