Bluetooth: MGMT: Fixes build warnings with C=1

This fixes the following warning when building with make C=1:

net/bluetooth/mgmt.c:3821:29: warning: restricted __le16 degrades to integer
net/bluetooth/mgmt.c:4625:9: warning: cast to restricted __le32

Fixes: 600a8749 ("Bluetooth: Implementation of MGMT_OP_SET_BLOCKED_KEYS.")
Fixes: 4c54bf2b ("Bluetooth: Add get/set device flags mgmt op")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>