fs/cifs: Simplify bool comparison.

Fix the follow warnings:

./fs/cifs/connect.c: WARNING: Comparison of 0/1 to bool variable
Reported-by: NAbaci Robot <abaci@linux.alibaba.com>
Signed-off-by: NJiapeng Zhong <abaci-bugfix@linux.alibaba.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

fs/cifs/connect.c

@@ -2628,7 +2628,7 @@ void reset_cifs_unix_caps(unsigned int xid, struct cifs_tcon *tcon,
 	} else if (ctx)
 		tcon->unix_ext = 1; /* Unix Extensions supported */
 
-	if (tcon->unix_ext == 0) {
+	if (!tcon->unix_ext) {
 		cifs_dbg(FYI, "Unix extensions disabled so not set on reconnect\n");
 		return;
 	}