wil6210: wmi: Correct misnamed function parameter 'ptr_'

wil6210: wmi: Correct misnamed function parameter 'ptr_'

Fixes the following W=1 kernel build warning(s):

 drivers/net/wireless/ath/wil6210/wmi.c:279: warning: Function parameter or member 'ptr_' not described in 'wmi_buffer_block'
 drivers/net/wireless/ath/wil6210/wmi.c:279: warning: Excess function parameter 'ptr' description in 'wmi_buffer_block'

Cc: Maya Erez <merez@codeaurora.org>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: wil6210@qti.qualcomm.com
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201102112410.1049272-2-lee.jones@linaro.org