Merge patch series "can: esd_usb: Fixes and improvements"

Stefan Mätje <stefan.maetje@esd.eu> says:

The first patch makes some error messages also print the error
code to achieve a higher significance. Removes also a duplicate
message and makes the register / unregister messages symmetric.

The second patch avoids emitting any error messages during the
disconnect of CAN-USB devices or the driver unload.

Changes in v2:
- Second patch:
  - Convert all occurrences of error status prints to use
    "ERR_PTR(err)" instead of printing the decimal value
    of "err".
  - Rename retval to err in esd_usb_read_bulk_callback() to
    make the naming of error status variables consistent
    with all other functions.

Link: https://patch.msgid.link/20250821143422.3567029-1-stefan.maetje@esd.eu
[mkl: only take paches 4+5, which are new features, adjust cover letter accordingly]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>