Note: the application still doesn't show the coordinates, just UTC
time received from sattellites.

The GPS icon blinks while searching for signal and is on when fixed

Note: still standalone, 'bear'-metal application, not yet hooked
to FreeRTOS

Implemented and tested some utility functions

The subject is the test program for the GPS.

This was actually wrong, the Antenova M10478 GPS module doesn't need a double
ON_OFF pin pulse, it just needs an ~150ms delay from the time its EXT_RST pin
is asserted to the time it can dump out data.

What was happening before is that we didn't have a delay in the gps_init
function before sending the on_off pulse, and this meant that the pulse was
missed by the module, which never turned on.

The added delay fixes this issue and we now need only a single pulse.

The problem was that one needs to STATICALLY allocate the buffer
that sends the data to the GPS. In this case, making the rxbuf
static inside gps/main.c fixed the problem.

For safety, the buffer inside usbdbg_puts() was also made static, and aligned
to a word (32-bit) boundary, as advised by the SiLabs USB device library.

usbled host-side s/w controls blinking the LEDs
EFM32 code in usbdcdc