ARM: ep93xx: ts72xx: Rewrite ts72xx_register_flash() to accept parameters

ARM: ep93xx: ts72xx: Rewrite ts72xx_register_flash() to accept parameters

This commit extend the ts72xx_register_flash() to accept passed parameters,
which makes it more reusable.

Now it is possible to accept ep93xx flash start address and partitions.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Acked-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>