spi: omap-100k: Remove unused pointer in omap1_spi100k_txrx_pio()

Remove unused devdata pointer 'spi100k' in function omap1_spi100k_txrx_pio().

Detected by Coverity: CID 1077869.

Signed-off-by: Christian Engelmayer <cengelma@gmx.at>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Mark Brown <broonie@linaro.org>