vulkan/swapchain: prefer bit depth over format in surface fmt selection

Fixes selecting 16-bits float formats for linear transfers.

Instead of: VK_FORMAT_B8G8R8A8_UNORM + VK_COLOR_SPACE_DISPLAY_P3_LINEAR_EXT we now select: VK_FORMAT_R16G16B16A16_SFLOAT + VK_COLOR_SPACE_DISPLAY_P3_LINEAR_EXT

Note that SFLOAT formats are already filtered out for non-linear transfers.