The Asus T200TA has an Broadcom 43340 chip. The 4.1.2 mainline kernel was installed and firmware from linux-firmware 1.146 Ubuntu package (based on upstream 75cc3ef8ba6712fd72c073b17a790282136cc743) There's a nvram-* file in /sys/firmware/efi/efivars. It has to be manually copied from there to /lib/firmware/brcm/brcmfmac-43340-sdio.txt. Such manual work should not be required. Used Ubuntu 15.04 as my distribution. Please let me know should I provide any other logs.
This sounds like a feature request. Getting a proper nvram file in place is a necessary evil. Most people have to complain with their laptop vendor or find it in a windows install package. Now in your case obtaining it is dead easy. Just a copy command and you are all set. I don't see much merit in having the driver digging in efi data.
Yep, but tell it to the people who start using Linux, with Windows background. For us it's ultra easy to copy one file, for them it might be overwhelming to dive into the filesystem and to anything manually.