spi/qspi: Add dual/quad spi read support

Support for multiple lines in SPI framework has been picked[1].
[1]: http://comments.gmane.org/gmane.linux.kernel.spi.devel/14420



Hence, adapting ti qspi driver to support multiple data lines for read.

Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>