vfio: selftests: Upgrade driver logging to dev_err()

vfio: selftests: Upgrade driver logging to dev_err()

Upgrade various logging in the VFIO selftests drivers from dev_info() to
dev_err(). All of these logs indicate scenarios that may be unexpected.
For example, the logging during probing indicates matching devices but
that aren't supported by the driver. And the memcpy errors can indicate
a problem if the caller was not trying to do something like exercise I/O
fault handling. Exercising I/O fault handling is certainly a valid thing
to do, but the driver can't infer the caller's expectations, so better
to just log with dev_err().

Suggested-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Alex Mastro <amastro@fb.com>
Tested-by: Alex Mastro <amastro@fb.com>
Reviewed-by: Raghavendra Rao Ananta <rananta@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20251126231733.3302983-10-dmatlack@google.com
Signed-off-by: Alex Williamson <alex@shazbot.org>