ath10k: Add wrapper function to ath10k debug

ath10k_dbg() is called in ath10k_process_rx() with huge set of arguments
which is causing CPU overhead even when debug_mask is not set.
Good improvement was observed in the receive side performance when call
to ath10k_dbg() is avoided in the RX path.

Since currently all debug messages are sent via tracing infrastructure,
we cannot entirely avoid calling ath10k_dbg. Therefore, call to
ath10k_dbg() is made conditional based on tracing config in the driver.

Trasmit performance remains unchanged with this patch; below are some
experimental results with this patch and tracing disabled.

mesh mode:

		w/o this patch          with this patch
Traffic       TP      CPU Usage      TP      CPU usage

TCP          840Mbps    76.53%      960Mbps    78.14%
UDP          1030Mbps   74.58%      1132Mbps   74.31%

Infra mode:

		w/o this patch          with this patch
Traffic        TP      CPU Usage      TP      CPU usage

TCP Rx       1241Mbps   80.89%      1270Mbps   73.50%
UDP Rx       1433Mbps   81.77%      1472Mbps   72.80%

Tested platform	: IPQ8064
hardware used	: QCA9984
firmware ver	: ver 10.4-3.5.3-00057

Signed-off-by: Kan Yan <kyan@chromium.org>
Signed-off-by: Venkateswara Naralasetty <vnaralas@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>