mtd: mtdoops: Don't write panic data twice

If calling mtdoops_write, don't also schedule work to be done later.

Although this appears to not be causing an issue, possibly because the
scheduled work will never get done, it is confusing.

Fixes: 016c1291 ("mtd: mtdoops: do not use mtd->panic_write directly")
Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200903034217.23079-1-mark.tomlinson@alliedtelesis.co.nz