Enables support for SPI SPL, QSPI and Spansion serial flash device
on the EVM. Configures pin muxes for QSPI mode.

Signed-off-by: Matt Porter <matt.porter@linaro.org>
Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>