mtd: rawnand: Fix spelling mistake waifunc() -> waitfunc()

There is a spelling mistake in a chip->legacy.waifunc(). Fix it.

Signed-off-by: Md Sadre Alam <quic_mdalam@quicinc.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230306144810.22078-1-quic_mdalam@quicinc.com