Bluetooth: btrtl: Fix a error code in rtl_load_config()

We accidentally return success if the kmemdup() fails.  It results in
a NULL dereference in the caller.

Fixes: 1110a2db

 ("Bluetooth: btrtl: Add RTL8822BE Bluetooth device")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>