Silence warning in CMake mips64 build.

Removed source file (aom_dsp/mips/add_noise_msa.c) from aom_dsp.cmake
to match the configure build.

Change-Id: I7f966afda209cff8949441bf30d757c19bcf65e7

aom_dsp/aom_dsp.cmake

diff --git a/aom_dsp/aom_dsp.cmake b/aom_dsp/aom_dsp.cmake
index c1f7e89..f00348c 100644
--- a/aom_dsp/aom_dsp.cmake
+++ b/aom_dsp/aom_dsp.cmake
@@ -147,7 +147,6 @@
     "${AOM_ROOT}/aom_dsp/mips/loopfilter_mb_vert_dspr2.c")
 
 set(AOM_DSP_COMMON_INTRIN_MSA
-    "${AOM_ROOT}/aom_dsp/mips/add_noise_msa.c"
     "${AOM_ROOT}/aom_dsp/mips/aom_convolve8_avg_horiz_msa.c"
     "${AOM_ROOT}/aom_dsp/mips/aom_convolve8_avg_msa.c"
     "${AOM_ROOT}/aom_dsp/mips/aom_convolve8_avg_vert_msa.c"