freedreno/a2xx: Stop using lower-to-source-mods.

Our copy propagation should be able to handle squashing fneg/fabs just
fine.  There's a goal in NIR of eliminating the source modifier flags, and
this gets us one less driver using them.
latest detached
Status Job ID Name Coverage
  Container
manual #2357864
aarch64 manual
arm_build
manual #2357865
aarch64 manual
arm_test
manual #2357866
windows shell 1809 mesa manual
windows_build_vs2019
manual #2357860
manual
x86_build
manual #2357863
manual
x86_build_old
manual #2357861
manual
x86_test-gl
manual #2357862
manual
x86_test-vk
 
  Meson X86 64
created #2357870
meson-clang
created #2357869
meson-classic
created #2357871
meson-clover
created #2357872
meson-clover-old-llvm
created #2357868
meson-gallium
created #2357867
meson-testing
created #2357873
meson-vulkan
 
  Scons
created #2357874
allowed to fail
scons-win64
 
  Meson Misc
created #2357876
aarch64
meson-arm64
created #2357877
aarch64
meson-arm64-build-test
created #2357875
aarch64
meson-armhf
created #2357879
meson-i386
created #2357882
meson-mingw32-x86_64
created #2357881
kvm
meson-ppc64el
created #2357880
kvm
meson-s390x
created #2357878
windows docker 1809 mesa
meson-windows-vs2019
 
  Freedreno
created #2357886
google-freedreno-db410c
arm64_a306_gles2
created #2357887
google-freedreno-db820c
arm64_a530_gles2
created #2357883
mesa-cheza
arm64_a630_gles2
created #2357885
mesa-cheza
arm64_a630_gles3
created #2357884
mesa-cheza
arm64_a630_gles31