Staging: rtl8187se: Fix warning symbol should be static

This patch solves the sparse warning: "symbol 'ieee80211_ccmp_aes_encrypt' was
not declared. Should it be static?"
Signed-off-by: Andreea-Cristina Bernat <bernat.ada@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8187se/ieee80211/ieee80211_crypt_ccmp.c

@@ -58,7 +58,7 @@ struct ieee80211_ccmp_data {
 	u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
 };
 
-void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm,
+static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm,
 				const u8 pt[16], u8 ct[16])
 {
 	crypto_cipher_encrypt_one((void *)tfm, ct, pt);