CH59x UART1 printf and uartdemo example

[biemster]

This example does printf on UART1 (rx,tx:PA8,PA9).

I #defined SetupUART like was done for ch32..., but I suspect that _write and putchar should be overloaded because of WEAK. I can change that easily if necessary.

Tested and working awesomely:

✔ ~/temp/CH570/ch32fun [ch59x-uartdemo L|✔] 
19:03 $ screen /dev/ttyUSB0 115200
ch32fun is awesome!
ch32fun is awesome!
ch32fun is aPA9 tx
PA9 tx
PA9 tx
PA9 tx
ch32fun is awesome!
ch32fun is awesome!
ch32fun
                                                                                                                                                                                                                  
[screen is terminating]
✔ ~/temp/CH570/ch32fun [ch59x-uartdemo L|✔] 
19:04 $ 

Also there are a bit more #defines in ch59xhw.h than necessary, but UART1 was mentioned in the interrupt from sleep stuff that I will be working on next so I included the whole sleep mode related #defines.

[cnlohr]

Looks good.