ath10k: move non-fatal warn logs to dbg level

During driver load below warn logs are printed in the console.
Since driver may not implement all wmi events sent by fw and
all of them are non-fatal, move this log to debug level to
remove un-necessary warn message on console.

[  361.887230] ath10k_snoc a000000.wifi: Unknown eventid: 16393
[  361.907037] ath10k_snoc a000000.wifi: Unknown eventid: 237569

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