ath10k: initialise struct ath10k_bus params to zero

ath10k: initialise struct ath10k_bus params to zero

This way we don't need to set every variable and give them to default, which is
zero. This is also safer in case we forgot to initalise a new field in some of
the bus modules.

Compile tested only.

Signed-off-by: Kalle Valo <kvalo@codeaurora.org>