rtl8192eu: fix -Wmissing-prototypes for 121 functions

- Mark 103 file-private functions as static (verified single-file usage)
- Add prototypes to headers for 10 cross-file functions:
  rtw_br_ext.h: nat25_db_expire/handle, nat25_handle_frame,
                dhcp_flag_bcast, scdb_findEntry
  rtw_recv.h: recv_decache, validate_recv_mgnt_frame
  rtw_mlme_ext.h: update_hidden_ssid
- Wrap rtw_btcoex.c definitions in #ifdef CONFIG_BT_COEXIST_SOCKET_TRX
  (declarations already guarded in header, definitions were not)
- Wrap rtw_get_xframe in #ifdef CONFIG_TX_AMSDU (same mismatch)
- Normalize CRLF->LF in driver sources before patching
  (rtw_chplan.c from upstream has Windows line endings)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: 2 people

lib/functions/compilation/patch/drivers_network.sh

@@ -181,6 +181,9 @@ driver_rtl8192EU() {
 		# fix compiler warnings - must be first before other patches
 		process_patch_file "${SRC}/patch/misc/wireless-rtl8192eu-Fix-compile-warnings.patch" "applying"
 
+		# fix -Wmissing-prototypes: static for file-private functions, prototypes in headers for cross-file
+		process_patch_file "${SRC}/patch/misc/wireless-rtl8192eu-Fix-missing-prototypes.patch" "applying"
+
 		process_patch_file "${SRC}/patch/misc/wireless-rtl8192eu-Fix-p2p-go-advertising.patch" "applying"
 
 		# fix compilation for kernels >= 5.4