OMAP3: am3517_evm: Add NAND MTD partitions with UBI/UBIFS support

- Add required UBI/UBIFS config definitions
- Add reasonable MTD partition layout
- Remove JFFS2 config definitions
- Drop some CFI verbage and definitions
- Make comment 'one-liners' truly one line
- Improve readability and content arrangement

Signed-off-by: Derald D. Woods <woods.technical@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>