panvk: Advertise support for VK_EXT_border_color_swizzle
Addresses the discussion in #6652 for panvk
I expected this MR to be a tad bigger but thanks to how GetPhysicalDeviceFeatures2 is now common between drivers, it was simple work
With this MR we went from 11.1% passed at dEQP-VK*border_swizzle* to 22.3% with no failures