wil6210: support devices with different PCIe bar size

wil6210 devices can have different PCIe bar size, hence get the
bar size from PCIe device instead of using a constant bar size.

Change-Id: I02fe3f05e184b141c9a5519dd97c3f2d2eb99baf
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Git-commit: d86d47164b227f01c3ec34c3f5a1613977d563eb
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git


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