csky: use asm-generic/mmu_context.h for no-op implementations

#define cpu_asid(mm)		(atomic64_read(&mm->context.asid) & ASID_MASK)

#define init_new_context(tsk,mm)	({ atomic64_set(&(mm)->context.asid, 0); 0; })

#define activate_mm(prev,next)		switch_mm(prev, next, current)

#define destroy_context(mm)		do {} while (0)

#define enter_lazy_tlb(mm, tsk)		do {} while (0)

#define deactivate_mm(tsk, mm)		do {} while (0)

void check_and_switch_context(struct mm_struct *mm, unsigned int cpu);

	flush_icache_deferred(next);

}

#include <asm-generic/mmu_context.h>

#endif /* __ASM_CSKY_MMU_CONTEXT_H */