fix(wifi): fix wifi link error when enable wifi debug

Link the library "libpp_dbg.a" to IRAM.

Author: dongheng

components/esp8266/linker.lf

@@ -1,7 +1,14 @@
 [mapping:pp]
 archive: libpp.a
 entries:
-    * (noflash_text)
+    if ESP8266_WIFI_DEBUG_LOG_ENABLE = n:
+        * (noflash_text)
+
+[mapping:pp_dbg]
+archive: libpp_dbg.a
+entries:
+    if ESP8266_WIFI_DEBUG_LOG_ENABLE = y:
+        * (noflash_text)
 
 [mapping:phy]
 archive: libphy.a