Avoid the example bitstream header to validate the bitstream that should
be loaded into the FPGA. The header is mostly 0xFFFFFFFF with a few
special values at a certain offsets and can be better described with the
offsets and their magic values.

As a drive by, this fixes/removes a broken check in the header
validation. The != operator has a higher precedence than ?: and this
check should have had parenthesis around the ?: expression:

	bin_header[i] != (byte_order == XILINX_BYTE_ORDER_BIT) ?
              bin_format[i] : __swab32(bin_format[i])

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Reviewed-by: Thomas Haemmerle <thomas.haemmerle@wolfvision.net>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>