Bluetooth: hci_qca: Remove redundant initializations to zero

The qca_data structure is allocated with kzalloc() and hence
zero-initialized. Remove a bunch of unnecessary explicit
initializations of struct members to zero.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>