Bluetooth: shell: Fix compile error with LL cmds included

Fixed compile error due to the missing header file
dependency on bluetooth/hci.h, for bt_addr_le_t, in the
Link Layer header file.

Merge of PR #475 introduced the new dependency that broke
compilation after merge of #474.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>