mtd: rawnand: intel: check the mtd name only after setting the variable

Move the check for mtd->name after the mtd variable has actually been
initialized.

While here, also drop the NULL assignment to the mtd variable as it's
overwritten later on anyways and the NULL value is never read.

Fixes: 0b1039f0 ("mtd: rawnand: Add NAND controller support on Intel LGM SoC")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210106140943.98072-1-martin.blumenstingl@googlemail.com