ath10k: configure access category for arp

ARP frames exchange does not work properly for UAPSD enabled AP.
ARP requests which arrives with access category 0 are processed
by network stack and send back with access category 0. FW changes
access category to 6. This is causing problems when UAPSD associated
STA is sleeping after has sent ARP request. Configure ARP access
category in FW to best effort (0) solves this problem. ARP frames
will be send with access category 0.

Simplify arp ac override functionality by removing redundant entry in
pdev param maping table. There should be only one entry in pdev param
map but enum has different name for different FW.

kvalo: change the warning message

Signed-off-by: Marek Puzyniak <marek.puzyniak@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>