score: add flush_dcahce_page and PG_dcache_dirty define

Signed-off-by: Cui Bixiong <bixiong@sunnorth.com.cn>
Signed-off-by: Chen Liqin <liqin.chen@sunplusct.com>

	modified:   arch/score/include/asm/cacheflush.h
	modified:   arch/score/mm/cache.c