resume pppos example on esp32s2

examples/protocols/pppos_client/CMakeLists.txt

@@ -2,6 +2,5 @@
 # in this exact order for cmake to work correctly
 cmake_minimum_required(VERSION 3.5)
 
-set(SUPPORTED_TARGETS esp32)
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 project(pppos_client)