Add an example that shows effects of FVP quantum param

Some of the greentea ticker tests failed on FVP. They were OK on the
CS300 FPGA (hardware). As it turned out, that was an expected behavior
of the Fast Models FVP. The FVP issues instructions in sets called
quantum at a point in time, waits, and then executes the next quantum.
This is really visible when polling a high-resolution timer like the
us_ticker. This was exactly the case for the failing ticker tests;
polling the us_ticker.

The example added here is supposed to show the effect of a `--quantum N`
option of the FVP. Set it to a lower value, i.e. 100 and observe a
behavior that is much more similar to the FPGA.

Signed-off-by: Filip Jagodzinski <filip.jagodzinski@arm.com>