radv: assert that colorAttachment is valid for CmdClearAttachment

This partially reverts a change from b7a93cbd ("radv: Handle
VK_ATTACHMENT_UNUSED in CmdClearAttachment") which fixed actual issues
but also started to accept invalid values for the colorAttachment
field.

This change asserts that the field is valid for the current pass.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: b7a93cbd ("radv: Handle VK_ATTACHMENT_UNUSED in CmdClearAttachment")
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
24 jobs for wip/djdeath/clear-attachment-fix in 56 minutes and 51 seconds (queued for 34 seconds)
Status Job ID Name Coverage
  Build+Test
passed #103664
build:make-gallium-drivers-other

00:09:09

passed #103663
build:make-gallium-drivers-radeonsi

00:07:19

passed #103662
build:make-gallium-drivers-swr

00:09:41

passed #103665
build:make-gallium-st-clover-llvm-39

00:09:44

passed #103666
build:make-gallium-st-clover-llvm-4

00:11:21

passed #103667
build:make-gallium-st-clover-llvm-5

00:06:24

passed #103668
build:make-gallium-st-clover-llvm-6

00:11:22

passed #103669
build:make-gallium-st-clover-llvm-7

00:07:21

passed #103670
build:make-gallium-st-other

00:07:24

passed #103661
build:make-loader-classic-dri

00:10:30

passed #103660
build:make-vulkan

00:04:59

passed #103656
build:meson-gallium-clover-llvm5

00:01:43

passed #103657
build:meson-gallium-clover-llvm6

00:01:53

passed #103658
build:meson-gallium-clover-llvm7

00:02:00

passed #103655
build:meson-gallium-drivers-other

00:02:10

passed #103654
build:meson-gallium-radeonsi

00:02:00

passed #103659
build:meson-gallium-st-other

00:02:11

passed #103653
build:meson-gallium-swr

00:03:56

passed #103652
build:meson-glvnd

00:02:06

passed #103651
build:meson-loader-classic-dri

00:02:29

passed #103650
build:meson-vulkan

00:02:21

passed #103672
build:scons-llvm

00:03:44

passed #103671
build:scons-nollvm

00:04:22

passed #103673
build:scons-swr

00:06:49