socfpga: Drop redundant save_boot_params

The save_boot_params function here is the same as the default weak one
from arch/arm/cpu/armv7/start.S, drop.

Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Vince Bridgers <vbridger@opensource.altera.com>
Cc: Chin Liang See <clsee@altera.com>
Cc: Marek Vasut <marex@denx.de>
Signed-off-by: Tom Rini <trini@ti.com>
Reviewed-by: Marek Vasut <marex@denx.de>