Duo's CPU combination is more complicated:
| BSP | B/L core| ISA | UART |
| ------------- | ------- |---------------- |-------|
| cv18xx_risc-v | Big | RISC-V C906 | UART0 |
| c906-little | Littel | RISC-V C906 | UART1 |
| cv18xx_aarch64| Big | ARM Cortex A53 | UART0 |
Printing ISA and big and small core information
during the boot process helps developers/testers
determine the CPU and serial port corresponding to
the current console.
In addition, the RTT logo printing has already
distinguished whether it is smart, so the bsp
printing no longer distinguishes.
Updated README to sync with this change.
Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
