ath10k-ct-firmware: Add support for QCA9886/QCA9888 firmware.

This firmware shoul have the same general feature set as the
rest of the 10.4 CT firmware (9984, 9980, etc).  Build-tested
only in LEDE, but firmware has been tested with ath10k-ct driver
on other OSs, so likely works just fine.

Signed-off-by: Ben Greear <greearb@candelatech.com>