vulkan: delete typo'd header

Two files exist in that directory:
- vulkan_xlib_randr.h
- vulkan_xlib_xrandr.h

Both were imported in 205c2715 ("vulkan: Update the XML and
headers to 1.1.70") with identical contents (ie. the
VK_EXT_acquire_xlib_display extension), but the former was never
included anywhere and can't be found upstream [1], while the latter is
included in vulkan.h and found upstream.

[1] https://github.com/KhronosGroup/Vulkan-Headers/tree/master/include/vulkan



Fixes: 205c2715 ("vulkan: Update the XML and headers to 1.1.70")
Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
(cherry picked from commit 344859c3)