wil6210: inline functions for vring hi/lo watermarks

Provide clear definition of the watermarks for the vring descriptor space.

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Git-commit: 5bb6423e8f23b755cb20c21aa896cc4d4baf6bc5
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Liron Kuch <lkuch@codeaurora.org>