BACKPORT: UPSTREAM: ath10k: add hw params for shadow register support

wcn3990 supports shadow register for ce write.

Add a hw param for shadow register support.

Signed-off-by: Rakesh Pillai <pillair@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
[govinds@codeaurora.org: resolve trivial merge conflicts in
drivers/net/wireless/ath/ath10k/core.c]
Change-Id: I0797078c50f7531ecaccc7c305db9f2d6c6e1835
Git-commit: b2e40d7ab8e2d36b455113df96dcbab0407e35c0
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Govind Singh <govinds@codeaurora.org>