vulkan/wsi/x11: Ensure we create at least minImageCount images.

vulkan/wsi/x11: Ensure we create at least minImageCount images.

Doom Eternal happily creates a swapchain with 2 images for IMMEDIATE...

This fixes a 10% performance issues with Doom Eternal for me.

Since the game only sets a minImageCount increasing till our own minimum
is totally okay.

CC: <stable@lists.freedesktop.org>
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/2684
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3156
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4368>