mtd: rawnand: Add support to dedicated function to set timings

With the current code if the board has an ONFI compliant NAND without
support to the get and set features, U-boot returns an ENOTSUP error when
trying to tune the timings which prevents the probe of the device.
Indeed onfi_set_features() return ENOTSUP error if set/get features is not
supported. In the case of timings we should not return ENOTSUP because we
can use the default timings. The NAND is already capable of listening at
its highest supported rate, so we assume in this case that it is fine to
skip the operation.

Fix it by adding an intermediate nand_onfi_set_timings() function which
does not error out if set/get feature is not supported.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>