wil6210: fix random failure to bring network interface up

Currently when we want to bring the interface up, we first
reset the device which causes the boot loader to run. Then
we halt the device CPU, load FW image and resume the device
CPU.
There are some boot loader versions which perform redundant
memory accesses even when idle. Halting the device CPU
while boot loader access memory can cause the device memory
controller to get stuck, the FW will fail to load and the
network interface will not come up.
For such boot loaders implement a workaround where we freeze
the boot loader before halting the device CPU, so it will not
perform any memory accesses.

Change-Id: Ie3cb043a7ea5ebda301e2750c082c14a4a9bfb4a
Signed-off-by: Lior David <liord@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Git-commit: 70bcc658c0b13d9e89033e1981daf0f431f39522
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git


Signed-off-by: Maya Erez <merez@codeaurora.org>