staging: rtl8723bs: delete extern declarations in core/rtw_wlan_util.c

staging: rtl8723bs: delete extern declarations in core/rtw_wlan_util.c

fix the following checkpatch issues:

WARNING: externs should be avoided in .c files
28: FILE: drivers/staging/rtl8723bs/core/rtw_wlan_util.c:28:
+extern unsigned char RTW_WPA_OUI[];
--
WARNING: externs should be avoided in .c files
29: FILE: drivers/staging/rtl8723bs/core/rtw_wlan_util.c:29:
+extern unsigned char WPA_TKIP_CIPHER[4];

Signed-off-by: Fabio Aiuto <fabioaiuto83@gmail.com>
Link: https://lore.kernel.org/r/0fa08b70af86b2ee88564179a22d908a643bed1f.1616503354.git.fabioaiuto83@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>