mtd: onenand: Check for error irq

For the possible failure of the platform_get_irq(), the returned irq
could be error number and will finally cause the failure of the
request_irq().
Consider that platform_get_irq() can now in certain cases return
-EPROBE_DEFER, and the consequences of letting request_irq() effectively
convert that into -EINVAL, even at probe time rather than later on.
So it might be better to check just now.

Fixes: 2c22120f ("MTD: OneNAND: interrupt based wait support")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220104162658.1988142-1-jiasheng@iscas.ac.cn