Add fast programmiong for CH32F1x device and blinking LED for status

[hlyi]

CH32F1x has two flash programming modes:

• half-word mode, which is compatible one with STM32F1x from flash programming point of view, but is much slower than STM32F1x
• page mode, which more 10x faster than half-word mode. The code change is to enable this mode.

Add blinking LED for DFU status:

• slow blinking when DFU is idle
• fast blinking when DFU is busy ( uploading, downloading or error condition)