f2fs: use inode pointer for {set, clear}_inode_flag

This patch refactors to use inode pointer for set_inode_flag and
clear_inode_flag.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 38d56f6..4a03076 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -617,9 +617,9 @@
 	f2fs_submit_page_mbio(&fio);
 
 	f2fs_update_data_blkaddr(&dn, newaddr);
-	set_inode_flag(F2FS_I(inode), FI_APPEND_WRITE);
+	set_inode_flag(inode, FI_APPEND_WRITE);
 	if (page->index == 0)
-		set_inode_flag(F2FS_I(inode), FI_FIRST_BLOCK_WRITTEN);
+		set_inode_flag(inode, FI_FIRST_BLOCK_WRITTEN);
 put_page_out:
 	f2fs_put_page(fio.encrypted_page, 1);
 recover_block: