mtd: spinand: winbond: Change Dummy Cycles for OCTALIO_OP

commit 4831290197a1ca00beed77b1a9631ae2893dd991 from
git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git



Change the dummy clock cycles for octalio_op from 16 to 20, so that,
the reads can run at higher frequencies.

Signed-off-by: Santhosh Kumar K <s-k6@ti.com>
Signed-off-by: Xulin Sun <xulin.sun@windriver.com>