mtd: onenand: Use mtd->oops_panic_write as condition

struct mtd_info has a flag oops_panic_write which is set when the write
operation is issued via the panic_write() callback. That allows controller
drivers to distinguish the panic write from a regular write.

Replace the open coded 'in_interrupt() | oops_in_progress' checks with a
check for that flag. in_interrupt() is an unrealiable indicator anyway as
it covers all sorts of atomic contexts not only hard and soft interrupt
service routines.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: linux-mtd@lists.infradead.org
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20201113141422.2214771-1-bigeasy@linutronix.de