mtd: rawnand: denali: remove unneeded casts in denali_{read, write}_pio

Since (u32 *) can accept an opaque pointer, the explicit casting
from (void *) to (u32 *) is redundant. Change the function argument type
to remove the casts.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>