Bugfixes for QCA6174.

While at it, to avoid confusion, also change the name of driver to
'btqca' in WHENCE file because that's what it is called in kernel images
(drivers/bluetooth/btqca.ko). Of course we cannot change the name of
directory 'qca' and that has to remain forever, but better to fix the
documentation to make it clear what driver this is.
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>