The bitstream header has 5 fields, that start with a char for the type.
Four fields have a big-ending length and a null-terminated string for
the design name, the part number, and the date and time of creation. The
last field is a big-endian 32 bit unsigned int for the size of the
bitstream.

Print this info when loading the bitstream.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>