Don't link px4_platform directly to uORB

Since uORB is split into kernel and userspace parts, it is no longer possible to just
link uORB into px4_platform, which is used in both kernel and user side.

Signed-off-by: Jukka Laitinen <jukkax@ssrc.tii.ae>

platforms/common/CMakeLists.txt

@@ -52,11 +52,10 @@ add_library(px4_platform
 	spi.cpp
 	${SRCS}
 )
-add_dependencies(px4_platform prebuild_targets)
+target_link_libraries(px4_platform prebuild_targets px4_work_queue)
 
 if (NOT "${PX4_BOARD}" MATCHES "io-v2")
 	add_subdirectory(uORB)
-	target_link_libraries(px4_platform PRIVATE uORB)
 endif()
 
 add_subdirectory(px4_work_queue)