Sorry for the late answer, haven't been keeping track of this thread.
Attached my kernel configfile below :
you can customize it to your liking ,but everything in [Device Drivers] > [MTD support] must not be changed.
If you would like to get access to the full uart device use my attached patch. It is located in "openwrt-directory"/target/linux/ramips/patches-3.10/
It is built for kernel 3.10.24, but it should work with other versions too. You have to change paths accordingly.
In order to get SPI,I2C access, "openwrt-directory"/target/linux/ramips/dts/CARAMBOLA.dts and "openwrt-directory"/target/linux/ramips/dts/rt3050.dtsi have to be modified.
I attached my cutom files below. In my rt3050.dtsi there is a "at25df321a" flash chip attached to SPI.
Edit:
You also have to activate uart in your DTS and DTSI files. See in my config files. You could probably just copy and paste them.
Hope i could help, have fun