fs: fat: use ATTR_ARCH instead of anonymous 0x20

Using constants instead of anonymous numbers increases code readability.

Fixes: 704df6aa0a28 ("fs: fat: refactor write interface for a file offset")
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index fc932df..7afc838 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -1191,7 +1191,8 @@
 		}
 
 		/* Set short name entry */
-		fill_dentry(itr->fsdata, itr->dent, filename, 0, size, 0x20);
+		fill_dentry(itr->fsdata, itr->dent, filename, 0, size,
+			    ATTR_ARCH);
 
 		retdent = itr->dent;
 	}