mtd: rawnand: macronix: nack the support of changing timings for one chip

The MX30LF2G18AC chip declares in its parameter page supporting
SET/GET_FEATURES but when it comes to timings, experience shows that it
is not the case.

Unflag this feature for this particular chip in the nand_parameters
structure to avoid unnecessary errors and downturns.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>