Fix include directories/files to have MPL3115A2 usages compile correctly

[Jashaszun]

Error:

build/stripped-firmware/code0.cc: In function ‘void code0::start()’:
build/stripped-firmware/code0.cc:122:59: error: ‘MPL3115A2_ADDRESS’ was not declared in this scope
     debug_uart.printf("Initializing altimeter@0x%X:\r\n", MPL3115A2_ADDRESS);
                                                           ^
build/stripped-firmware/code0.cc:124:9: error: ‘class MPL3115A2’ has no member named ‘setOversampleRate’
     alt.setOversampleRate(0b000);
         ^
build/stripped-firmware/code0.cc:125:9: error: ‘class MPL3115A2’ has no member named ‘setModeStandby’
     alt.setModeStandby();
         ^
build/stripped-firmware/code0.cc:126:9: error: ‘class MPL3115A2’ has no member named ‘setModeAltimeter’
     alt.setModeAltimeter();
         ^
build/stripped-firmware/code0.cc:127:9: error: ‘class MPL3115A2’ has no member named ‘setModeActive’
     alt.setModeActive();
         ^