Return real strings for DAP_GetProductString() and DAP_GetVendorString().

[bkuschak]

Return meaningful strings that the host can display:

Info : Using CMSIS-DAPv2 interface with VID:PID=0x1209:0xda42, serial=46534E0011163646461C0900
Info : CMSIS-DAP: SWD supported
Info : CMSIS-DAP: Atomic commands supported
Info : CMSIS-DAP: Test domain timer supported
Info : CMSIS-DAP: UART via USB COM port supported
Info : CMSIS-DAP: FW Version = 2.1.0
Info : CMSIS-DAP: Serial# = 46534E0011163646461C0900
Info : CMSIS-DAP: Vendor = https://github.com/devanlai/dap42
Info : CMSIS-DAP: Product = DAP103-BLUEPILL
Info : CMSIS-DAP: Product FW Version = 2.0.0
Info : CMSIS-DAP: Interface Initialised (SWD)
Info : SWCLK/TCK = 1 SWDIO/TMS = 1 TDI = 0 TDO = 0 nTRST = 0 nRESET = 1
Info : CMSIS-DAP: Interface ready

Tested with DAP103 Blue Pill only but it should work for the other boards also. Due to the way the code is structured, the patch is repetitive. It could be optimized, but I opted not to make any structural changes.