wil6210: remove wil_to_pcie_dev()

There is no need to obtain physical device through
wil->pdev->dev path, as it is done by this macro.
The same device already stored as wiphy's device, thus
wil_to_dev() returns the same device as wil_to_pcie_dev()

Remove unnecessary macros, this allows to drop dependency
by pci.h in the firmware download code.

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>