mtd: spinand: Add late_init for W25N01JW and W35N01JW

commit b330991759e4d4db58ee791f91601004ae99310d from
git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git



Post initialisation of a NAND flash device, some require a unique
set of configuration to run at optimal speeds/functionality.

In W25N01JW, HS bit needs to be set in Status Register 4 to run at
higher frequencies.

In W35N01JW, IO Mode and Dummy Clocks needs to be set correctly in
Volatile Configuration Register according to the mode and frequency.

So, add a late_init function to carry out these operations.

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