uboot-imx

zynq: spi: Remove unnecessary error condition

Removed the unnecessary error check from spi_xfer
as the bitlen zero is possible now to deassert the
chip select for which no data is required to be transfered.

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>