OneNAND: Remove unused read_spareram

Remove unused read_spareram and add unlock_all as kernel does

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
diff --git a/drivers/mtd/onenand/onenand_base.c b/drivers/mtd/onenand/onenand_base.c
index d482437..368fa6e 100644
--- a/drivers/mtd/onenand/onenand_base.c
+++ b/drivers/mtd/onenand/onenand_base.c
@@ -1010,7 +1010,7 @@
 		if (ret)
 			break;
 
-		this->read_spareram(mtd, 0, ONENAND_SPARERAM, buf, column, thislen);
+		this->read_bufferram(mtd, 0, ONENAND_SPARERAM, buf, column, thislen);
 		read += thislen;
 		if (read == len)
 			break;
@@ -2104,8 +2104,6 @@
 
 	if (!this->read_bufferram)
 		this->read_bufferram = onenand_read_bufferram;
-	if (!this->read_spareram)
-		this->read_spareram = onenand_read_bufferram;
 	if (!this->write_bufferram)
 		this->write_bufferram = onenand_write_bufferram;