rockchip: pinebook-pro: default to SPI bus 1 for SPI-flash

SPI flash on this machine is located on bus 1, default to using bus 1
for SPI flash and stop aliasing it to bus 0.

Signed-off-by: Hugh Cole-Baker <sigmaris@gmail.com>
Suggested-by: Simon Glass <sjg@chromium.org>
Fixes: c4cea2bb ("rockchip: Enable building a SPI ROM image on bob")