Streamline chip-selection features by omitting packaging and temperature suffixes

[YingliangCai]

I bought a new CH32V006 development board featuring the CH32V006K8U7 chip. According to the official datasheet, the only difference between the chips ending in "7" and those ending in "6" is a wider operating temperature range; all other performance metrics and features are identical.
I tested compilation using the ch32v006k8u6 feature in ch32-hal, and it compiles successfully, though selecting a different suffix feels a bit strange and counterintuitive during development.
Based on the official naming conventions, the last two characters of the part number only represent the packaging type and temperature range. Therefore, I would like to suggest streamlining the chip-selection features by stripping these suffixes. For example, shortening ch32v006k8u6 down to just ch32v006k8.

[aq1018]

Im pretty sure there is no code differences. It's there mostly for completeness. You can use either one.

If you want to do it for the v00X series I think it's fine. If you send a PR I will approve.