staging: rtl8723bs: use WLAN_EID_VENDOR_SPECIFIC

Replace unique WLAN_EID_GENERIC, _WPA_IE_ID_, _SSN_IE_1_, and
_VENDOR_SPECIFIC_IE_ macros with kernel provided WLAN_EID_VENDOR_SPECIFIC
from linux/ieee80211.h.

Signed-off-by: Ross Schmidt <ross.schm.dev@gmail.com>
Link: https://lore.kernel.org/r/20201208040733.379197-3-ross.schm.dev@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>