nand: Add SPL_NAND support to mxc_nand_spl

nand: Add SPL_NAND support to mxc_nand_spl

Add support for generic NAND SPL via the SPL framework into the
mxc_nand_spl driver. This is basically just a simple rename and
publication of the already implemented functions. To avoid the
bare-bones functions getting in the way of the NAND_SPL, build
them only if CONFIG_SPL_FRAMEWORK is not defined.

Also make sure the requested payload is aligned to full pages,
otherwise this simple driver fails to load the last page.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
Cc: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Tom Rini <trini@ti.com>
Acked-by: Scott Wood <scottwood@freescale.com>