mtd: rawnand: fsl_elbc: Propagate HW ECC settings to HW

It is possible that current chip->ecc.engine_type value does not match to
configured HW value (if HW ECC checking and generating is enabled or not).

This can happen with old U-Boot bootloader version which either does not
initialize NAND (and let it in some default unusable state) or initialize
NAND with different parameters than what is specified in kernel DTS file.

So if kernel chose to use some chip->ecc.engine_type settings (e.g. from
DTS file) then do not depend on bootloader HW configuration and configures
HW ECC settings according to chip->ecc.engine_type value.

BR_DECC must be set to BR_DECC_CHK_GEN when HW is doing ECC (both
generating and checking), or to BR_DECC_OFF when HW is not doing ECC.

This change fixes usage of SW ECC support in case bootloader explicitly
enabled HW ECC support and kernel DTS file has specified to use SW ECC.
(Of course this works only in case when NAND is not a boot device and both
bootloader and kernel are loaded from different location, e.g. FLASH NOR.)

Fixes: f6424c22 ("mtd: rawnand: fsl_elbc: Make SW ECC work")
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230128134111.32559-1-pali@kernel.org