Increase DH key size in the hostapd.conf example

OpenSSL is moving to use 2048-bit DH key size as the default with
dhparam. Increase the value in the hostapd.conf to match that to reduce
likelihood of ending up using a shorter key.

Signed-off-by: Jouni Malinen <j@w1.fi>

hostapd/hostapd.conf

@@ -790,7 +790,7 @@ eap_server=0
 # is in DSA parameters format, it will be automatically converted into DH
 # params. This parameter is required if anonymous EAP-FAST is used.
 # You can generate DH parameters file with OpenSSL, e.g.,
-# "openssl dhparam -out /etc/hostapd.dh.pem 1024"
+# "openssl dhparam -out /etc/hostapd.dh.pem 2048"
 #dh_file=/etc/hostapd.dh.pem
 
 # OpenSSL cipher string