Bluetooth: btmrvl: fix compilation warning

This patch fixes a compile warnning "dump_num maybe used uninitialized in
this function".

Signed-off-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>