BROM: setup clocks and pinmux for SPI-NOR

Document the setup of clocks and pinmuxing when booting via SPI-NOR

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
Add spi_setup_dma

there seems to be a recursive loop here I don't quite understand yet

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
Merge pull request #3 from oliv3r/patch-1

BROM: setup clocks and pinmux for SPI-NOR