8148 add spi driver

http://blog.csdn.net/zouwen198317/article/details/8452209

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/366275

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/382636

http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/382636

http://processors.wiki.ti.com/index.php/TI81XX_PSP_McSPI_Driver_User_Guide

http://blog.csdn.net/droidphone/article/details/23932447

http://processors.wiki.ti.com/index.php/Category:DaVinci_Linux

http://processors.wiki.ti.com/index.php/DM814x_AM387x_PSP_User_Guide

http://processors.wiki.ti.com/index.php?title=TI81XX_PSP_McSPI_Driver_User_Guide&redirect=no

http://e2e.ti.com/support/arm/sitara_arm/f/791/t/327117