mtd: nand: raw: Fix CONFIG_SYS_NAND_DRIVER_ECC_LAYOUT behavior

The purpose of "mtd: nand: raw: allow to disable unneeded ECC layouts"
was to allow disabling the default ECC layouts if a driver is known to
provide its own ECC layout. However, this commit did the opposite and
disabled the default layout when it was _not_ selected.

It breaks all the NAND drivers not providing their own ECC layout this
patch fix this situation.

It was tested with the lpc32xx_nand_slc driver.

Fixes: a38c3af8 ("mtd: nand: raw: allow to disable unneeded ECC layouts")
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Tested-by: Eugen Hristev <eugen.hristev@microchip.com>