ath10k: bump up FW API to 5

Firmware 10.2.4.48-3 now supports management frames over HTT feature and has
ATH10K_FW_FEATURE_HAS_WMI_MGMT_TX. But as 10.2.4 branch has conflicting HTT ids
patch "ath10k: add ATH10K_FW_IE_HTT_OP_VERSION" is needed to fix the issue.
Older ath10k versions don't have support that support and to maintain backwards
compatibility we need bump up the FW API to 5 not break older versions.

Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>