Tests: Fix code style on system tests

src/systemcmds/tests/test_bson.c

src/systemcmds/tests/test_conv.cpp

src/systemcmds/tests/test_dataman.c

src/systemcmds/tests/test_eigen.cpp

src/systemcmds/tests/test_file.c

src/systemcmds/tests/test_file2.c

src/systemcmds/tests/test_float.c

src/systemcmds/tests/test_hrt.c

src/systemcmds/tests/test_mathlib.cpp

src/systemcmds/tests/test_mixer.cpp

src/systemcmds/tests/test_mount.c

src/systemcmds/tests/test_ppm_loopback.c

src/systemcmds/tests/test_sensors.c

src/systemcmds/tests/test_servo.c

src/systemcmds/tests/test_time.c

src/systemcmds/tests/test_uart_loopback.c

src/systemcmds/tests/tests_main.c