mtd: rawnand: Fix nand_erase_op delay

NAND_OP_CMD() expects a delay parameter in nanoseconds.
The delay value is wrongly given in milliseconds.

Fix the conversion macro used in order to set this
delay in nanoseconds.

Fixes: d7a773e8 ("mtd: rawnand: Access SDR and NV-DDR timings through a common macro")
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20211119150316.43080-2-herve.codina@bootlin.com