Your very new device, Qualcomm Atheros Device [168c:003e], is covered in the mainline kernel version 4.0: http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.0-vivid/ The module ath10k_pci covers the subject device:
modinfo ath10k_pci
filename: /lib/modules/4.0.1-040001-generic/kernel/drivers/net/wireless/ath/ath10k/ath10k_pci.ko
firmware: ath10k/QCA988X/hw2.0/board.bin
firmware: ath10k/QCA988X/hw2.0/firmware-3.bin
firmware: ath10k/QCA988X/hw2.0/firmware-2.bin
firmware: ath10k/QCA988X/hw2.0/firmware.bin
license: Dual BSD/GPL
description: Driver support for Atheros QCA988X PCIe devices
author: Qualcomm Atheros
srcversion: 837C8B320227AB6A933D58D
alias: pci:v0000168Cd0000003Esv*sd*bc*sc*i*
alias: pci:v0000168Cd0000003Csv*sd*bc*sc*i*
<snip>
As you can see, the driver requires firmware. My default 15.04 install includes most of it. If firmware is an issue, according to dmesg, I suggest you do:
sudo apt-get install git
git clone https://github.com/sumdog/ath10k-firmware.git
cd ath10k-firmware/ath10k
sudo cp -r QCA6174/ /lib/firmware/ath10k
Correct the permissions of the files:
sudo chmod +x /lib/firmware/ath10k/QCA6174/hw2.1/*
Now unload and reload the driver:
sudo modprobe -r ath10k_pci && sudo modprobe ath10k_pci
And check:
dmesg | grep ath
I have been unable to find cal-pci-000:03:0.0.bin anywhere, nor any method to extract it by any means. I did read that a module parameter may help. Let's try:
sudo -i
echo "options ath10k_core skip_otp=y" > /etc/modprobe.d/ath10k_core.conf
exit
Reboot. Check as above.
If you need guidance about how to install the 4.0 kernel, please check here: http://ubuntuhandbook.org/index.php/2015/04/upgrade-to-linux-kernel-4-0-in-ubuntu/