wil6210: writeable ITR registers

Interrupt threshold registers may be written to.

Change-Id: Ib6a8758f44a1fff26470e4fab3525271711c78c7
Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Git-commit: 4b63261c7d203472a1670d4199ee7754d52150e9
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-testing.git


Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>