ggml : fix ppc64le build (#13176)

Build fails with compilation error on power pc.
This patch fixes the same.

Tested with unit tests run via
 --build <build_dir> && cd <build_dir> && make test

Signed-off-by: Shalini Salomi Bodapati <[email protected]>

Author: shalinib-ibm

ggml/src/ggml-cpu/simd-mappings.h

@@ -341,7 +341,7 @@ static inline void __avx_f32cx8_store(ggml_fp16_t *x, __m256 y) {
 #define GGML_F32_EPR  4
 
 #define GGML_F32x4              vector float
-#define GGML_F32x4_ZERO         0.0f
+#define GGML_F32x4_ZERO         {0.0f}
 #define GGML_F32x4_SET1         vec_splats
 #define GGML_F32x4_LOAD(p)      vec_xl(0, p)
 #define GGML_F32x4_STORE(p, r)  vec_xst(r, 0, p)