spi/qspi: set correct platform drvdata in ti_qspi_probe()

The ti_qspi_remove() use the platform drvdata as a type of
struct ti_qspi, we should pass correct platform drvdata to
platform_set_drvdata() in ti_qspi_probe().

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Mark Brown <broonie@linaro.org>