MIPS: Lasat: Fix compilation

Header needed for current_cpu_data which expands to smp_processor_id().
However, linux/smp.h can't be included into asm/cpu-info.h due to horrible
circular dependencies, so plug it here.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>