Add a flag that is passed to the write_init() callback,
indicating that the SPI bitstream starts with LSB first.
SPI controllers usually send data with MSB first. If an
FPGA expects bitstream data as LSB first, the data must
be reversed either by the SPI controller or by the driver.

Alternatively the bitstream could be prepared as bit-reversed
to avoid the bit-swapping while sending. This flag indicates
such bit-reversed SPI bitstream. The low-level driver will
deal with the flag and perform bit-reversing if needed.
Signed-off-by: NAnatolij Gustschin <agust@denx.de>
Signed-off-by: NJoshua Clayton <stillcompiling@gmail.com>
Signed-off-by: NAlan Tull <atull@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>