fix: Fix compiler warning about uninitialized inp_pos

This should not have been reachable, but it warns on some compliers

Branch: GraniteMoEShared

Signed-off-by: Gabe Goodhart <ghart@us.ibm.com>

Author: gabe-l-hart

src/llama-model.cpp

@@ -12215,11 +12215,8 @@ struct llm_build_granite : public llm_graph_context {
 
         inpL = build_inp_embd(model.tok_embd);
 
-        // inp_pos - used for rope if enabled
+        // inp_pos - built only if rope enabled
         ggml_tensor * inp_pos;
-        if (use_rope) {
-            inp_pos = build_inp_pos();
-        }
 
         auto * inp_attn = build_attn_inp_kv_unified();
 
@@ -12262,6 +12259,10 @@ struct llm_build_granite : public llm_graph_context {
                 Vcur = ggml_reshape_3d(ctx0, Vcur, n_embd_head, n_head_kv, n_tokens);
 
                 if (use_rope) {
+
+                    if (!inp_pos) {
+                        inp_pos = build_inp_pos();
+                    }
                     ggml_tensor * rope_factors = model.get_rope_factors(n_ctx_per_seq, il);
                     Qcur = ggml_rope_ext(
                             ctx0, Qcur, inp_pos, rope_factors,