serial: finally working communcation at 115200

Signed-off-by: Michael Geszkiewicz <micges@wp.pl>
lbp16: move FPGA reset and reload to common place as now both ethernet and serial hm2 boards use them

Signed-off-by: Michael Geszkiewicz <micges@wp.pl>
serial: read and write uses ppoll for waiting for writing or data.

This resolve problems with lost bytes during flash id read or flash verification.

Signed-off-by: Michael Geszkiewicz <micges@wp.pl>
serial: support flash write and verify. Also increase timeouts on write and read to support waiting for long flash operations like erase and write_page

Signed-off-by: Michael Geszkiewicz <micges@wp.pl>