ARM: OMAP3: Get rid of omap3_gp_romcode_call and replace with omap_smc1

omap_smc1 is now generic enough to remove duplicate
omap3_gp_romcode_call logic that omap3 introduced.

As part of this change, move to using the generic lowlevel_init.S for
omap3 as well.

Signed-off-by: Nishanth Menon <nm@ti.com>
Tested-by: Matt Porter <mporter@konsulko.com>
Reviewed-by: Tom Rini <trini@konsulko.com>