OMAP3: Remove unused define CONFIG_OMAP3_*_DDR

This patch removes the unused definitions:
CONFIG_OMAP3_MICRON_DDR
CONFIG_OMAP3_NUMONYX_DDR
CONFIG_OMAP3_INFINEON_DDR

Signed-off-by: Thomas Weber <weber@corscience.de>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Acked-by: Luca Ceresoli <luca.ceresoli@comelit.it>