[U-Boot] Adding support to Technexion TAM3517 SOM

This patches adds support for the Technexion's SOM TAM3517 based on a TI AM3517. In agreement with Tapani Utrianen, this patchset superseeds the recent patches sent to the ML by him with the same purpose.

This patchset requires the patchset for the AM3517 and EMAC posted by Ilya Yanok, and not yet merged into mainline. Ilya's patches must be applied first before this patchset.

[PATCH 1/2] ARM: omap3: added common configuration for Technexion [PATCH 2/2] ARM: omap3: add support to Technexion twister board