anv: Lower ViewIndex to zero when multiview is disabled

Vulkan spec says

    If multiview is enabled in the render pass, this value will be one
    of the bits set in the view mask of the subpass the pipeline is
    compiled against. If multiview is not enabled in the render pass,
    this value will be zero.

Closes: #4446
Fixes: 0db70703 ("anv/pipeline: Add shader lowering for multiview")
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <!9574>
35 jobs for !9574 with r/anv-fix-multiview in 5 minutes and 32 seconds (queued for 3 seconds)
latest detached
Status Job ID Name Coverage
  Sanity
passed #8004463
sanity

00:00:09

 
  Container
passed #8004466
aarch64
arm_build

00:00:18

passed #8004467
arm_test-base

00:00:17

passed #8004468
windows shell 1809 mesa
windows_build_vs2019

00:00:13

passed #8004464
x86_build-base

00:00:18

passed #8004465
x86_test-base

00:00:18

 
  Container 2
passed #8004476
android_build

00:00:28

passed #8004479
arm64_test

00:00:22

passed #8004480
armhf_test

00:00:32

passed #8004473
i386_build

00:00:22

passed #8004469
kernel+rootfs_amd64

00:01:31

passed #8004470
aarch64
kernel+rootfs_arm64

00:01:12

passed #8004471
aarch64
kernel+rootfs_armhf

00:00:10

passed #8004474
ppc64el_build

00:00:29

passed #8004475
s390x_build

00:00:53

passed #8004472
x86_build

00:00:25

passed #8004477
x86_test-gl

00:00:52

passed #8004478
x86_test-vk

00:00:28

 
  Meson X86 64
passed #8004486
meson-clang

00:02:19

passed #8004487
meson-clover

00:03:52

passed #8004483
meson-clover-testing

00:02:04

passed #8004484
gstreamer
meson-gallium

00:03:30

passed #8004485
meson-release

00:02:49

passed #8004481
meson-testing

00:02:51

passed #8004482
meson-testing-asan

00:03:42

passed #8004488
meson-vulkan

00:02:03

 
  Build Misc
passed #8004489
meson-android

00:01:55

passed #8004491
aarch64
meson-arm64

00:01:33

passed #8004492
aarch64
meson-arm64-asan

00:03:00

passed #8004493
aarch64
meson-arm64-build-test

00:01:29

passed #8004490
aarch64
meson-armhf

00:01:30

passed #8004494
meson-i386

00:01:33

passed #8004497
meson-mingw32-x86_64

00:03:00

passed #8004496
kvm
meson-ppc64el

00:02:15

passed #8004495
kvm
meson-s390x

00:02:16