firmware: change kernel read fail to dev_dbg()

firmware: change kernel read fail to dev_dbg()

When we now use the new kernel_read_file_from_path() we
are reporting a failure when we iterate over all the paths
possible for firmware. Before using kernel_read_file_from_path()
we only reported a failure once we confirmed a file existed
with filp_open() but failed with fw_read_file_contents().

With kernel_read_file_from_path() both are done for us and
we obviously are now reporting too much information given that
some optional paths will always fail and clutter the logs.

fw_get_filesystem_firmware() already has a check for failure
and uses an internal flag, FW_OPT_NO_WARN, but this does not
let us capture other unxpected errors. This enables that
as changed by Neil via commit:

"firmware: Be a bit more verbose about direct firmware loading failure"

Reported-by: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>