mtd: nand: use the nand_read_subpage index everywhere
mtd: nand: use the nand_read_subpage index everywhere

Now that the index variable is correctly set earlier in this function
we can use it in other places that compute the same thing too.

Signed-off-by: Ron Lee <b937b287f61b7a223d4aac55072db1a5381d3bb3@debian.org>
Signed-off-by: Brian Norris <ac73eed4b8a8c9127255a2696c52b2e7503720b8@gmail.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs