boards: add new spi+i2c config

Chip-select and SPI initialization uses the new config, whereas the drivers
still use the existing defines.

The configuration in board_config.h can be removed after all drivers are
updated.

platforms/common/CMakeLists.txt

@@ -41,13 +41,13 @@ endif()
 
 add_library(px4_platform
 	board_identity.c
-	#i2c.cpp
-	#i2c_spi_buses.cpp
+	i2c.cpp
+	i2c_spi_buses.cpp
 	module.cpp
 	px4_getopt.c
 	px4_cli.cpp
 	shutdown.cpp
-	#spi.cpp
+	spi.cpp
 	${SRCS}
 	)
 add_dependencies(px4_platform prebuild_targets)