Silence unnecessary messages (Fixes #240)

[rewolff]

As requested. The startup of st-util is now:

assurancetourix:~> ~/stm32/stlink.git2/build/Release/src/gdbserver/st-util -m
st-util 1.6.0-33-gb8813fa-dirty
2020-03-21T16:07:15 INFO common.c: F0xx small: 4 KiB SRAM, 16 KiB flash in 1 KiB pages.
2020-03-21T16:07:15 INFO gdb-server.c: Listening at *:4242...

The user may want the "listening at" message and the "what's connected" message has been reduced from two lines to just one. It now contains just the info that normal users may want to know.: stuff that helps determine if say the right target is connected.

I removed all the "device" parts of the strings in the description of the chipID table.
Some of the "description" entries in the table had a check for say a CHIPID_F412 and then proceded to call the device an F4xx. Lets just call it F412 then. But maybe there are other devices that share the same chipID let me know if you find one.

[Nightwalker-87]

Info: Merge is going to wait until Travis CI maintenance has successfully concluded. Used services are currently limited or are not available at all.

[Nightwalker-87]

@rewolff: Thank you for your efforts!