app/bbdev: handle endianness of test data

app/bbdev: handle endianness of test data

With data input, output and harq also supported in big
endian format, this patch updates the testbbdev application
to handle the endianness conversion as directed by the
the driver being used.

The test vectors assumes the data in the little endian order, and
thus if the driver supports big endian data processing, conversion
from little endian to big is handled by the testbbdev application.

Signed-off-by: Nipun Gupta <nipun.gupta@nxp.com>
Acked-by: Akhil Goyal <gakhil@marvell.com>
Acked-by: Nicolas Chautru <nicolas.chautru@intel.com>