platforms: link libatomic only on emlid navio2 (raspberry pi)

Linking to libatomic is only required for targets such as Raspberry Pi but not on for normal x86/x86_64 Linux builds.

platforms/posix/CMakeLists.txt

@@ -68,7 +68,7 @@ else()
 	)
 
 	if(NOT APPLE)
-		target_link_libraries(px4 PRIVATE atomic rt)
+		target_link_libraries(px4 PRIVATE rt)
 	endif()
 
 	target_link_libraries(px4 PRIVATE modules__uORB)
@@ -107,12 +107,15 @@ if(EXISTS "${PX4_BOARD_DIR}/cmake/upload.cmake")
 endif()
 
 
-if ("${PX4_BOARD}" MATCHES "beaglebone_blue")
+if("${PX4_BOARD}" MATCHES "beaglebone_blue")
 	target_link_libraries(px4 PRIVATE robotics_cape)
 	add_dependencies(df_driver_framework librobotcontrol)
 	add_dependencies(df_mpu9250 librobotcontrol)
 
-elseif ("${PX4_BOARD}" MATCHES "sitl")
+elseif("${PX4_BOARD}" MATCHES "emlid_navio2")
+	target_link_libraries(px4 PRIVATE atomic)
+
+elseif("${PX4_BOARD}" MATCHES "sitl")
 
 	include(sitl_target)
 	if(BUILD_TESTING)