boards: arm: 96b_carbon: Add 3.3v Low speed connector support

Add support for 3.3v Low speed connector available on the Carbon
board inorder to access peripherals in a board independent way.

Following peripherals are supported:

1. 8-GPIOs
2. I2C0
3. SPI0
4. UART0
5. UART1

Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>