spi/xilinx: Fix access invalid memory on xilinx_spi_tx
spi/xilinx: Fix access invalid memory on xilinx_spi_tx

On 1 and 2 bytes per word, the transfer of the 3 last bytes will access
memory outside tx_ptr.

Although this has not trigger any error on real hardware, we should
better fix this.

Fixes: 24ba5e593f391507 (Remove rx_fn and tx_fn pointer)
Signed-off-by: Ricardo Ribalda Delgado <39bb74b16720293e1449e36465485b27216fbd6d@gmail.com>
Signed-off-by: Mark Brown <b51b9a92386687a9ac927cebfa0f978adeb8cea5@kernel.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs