rockchip: bootrom: Sync bootsource id enum from bootrom

Add more bootsource id:
1. BROM_BOOTSOURCE_UNKNOWN
2. BROM_BOOTSOURCE_I2C
3. BROM_BOOTSOURCE_SPI

Signed-off-by: Jason Zhu <jason.zhu@rock-chips.com>
[jonas@kwiboo.se: Update commit message]
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>