omap3: Introduce weak misc_init_r

Introduce a __weak misc_init_r function that just runs dieid_num_r().
Remove misc_init_r from cm_t35, mcx, omap3_logic and mt_ventoux as this was
all they did for misc_init_r.

Cc: Igor Grinberg <grinberg@compulab.co.il>
Cc: Ilya Yanok <yanok@emcraft.com>
Cc: Peter Barada <peter.barada@logicpd.com>
Cc: Stefano Babic <sbabic@denx.de>
Signed-off-by: Tom Rini <trini@ti.com>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>