fix ufs_isblockset()

static inline int _ubh_isblockset_(struct ufs_sb_private_info * uspi,

	struct ufs_buffer_head * ubh, unsigned begin, unsigned block)

{

	u8 mask;

	switch (uspi->s_fpb) {

	case 8:

	    	return (*ubh_get_addr (ubh, begin + block) == 0xff);

	case 4:

		return (*ubh_get_addr (ubh, begin + (block >> 1)) == (0x0f << ((block & 0x01) << 2)));

		mask = 0x0f << ((block & 0x01) << 2);

		return (*ubh_get_addr (ubh, begin + (block >> 1)) & mask) == mask;

	case 2:

		return (*ubh_get_addr (ubh, begin + (block >> 2)) == (0x03 << ((block & 0x03) << 1)));

		mask = 0x03 << ((block & 0x03) << 1);

		return (*ubh_get_addr (ubh, begin + (block >> 2)) & mask) == mask;

	case 1:

		return (*ubh_get_addr (ubh, begin + (block >> 3)) == (0x01 << (block & 0x07)));

		mask = 0x01 << (block & 0x07);

		return (*ubh_get_addr (ubh, begin + (block >> 3)) & mask) == mask;

	}

	return 0;	

}