Pica/VertexShader: Fixed LOOP with more than one iteration.

Previously it wouldn't jump back to the start of the loop code once it reached the end of the block.
Fixes the texture problems in a lot of games.

src/video_core/vertex_shader.cpp

@@ -90,6 +90,7 @@ struct VertexShaderState {
         u8 repeat_counter;  // How often to repeat until this call stack element is removed
         u8 loop_increment;  // Which value to add to the loop counter after an iteration
                             // TODO: Should this be a signed value? Does it even matter?
+        u32 loop_address;   // The address where we'll return to after each loop iteration
     };
 
     // TODO: Is there a maximal size for this?
@@ -115,6 +116,8 @@ static void ProcessShaderCode(VertexShaderState& state) {
                 if (top.repeat_counter-- == 0) {
                     state.program_counter = &shader_memory[top.return_address];
                     state.call_stack.pop();
+                } else {
+                    state.program_counter = &shader_memory[top.loop_address];
                 }
 
                 // TODO: Is "trying again" accurate to hardware?
@@ -129,7 +132,7 @@ static void ProcessShaderCode(VertexShaderState& state) {
         static auto call = [](VertexShaderState& state, u32 offset, u32 num_instructions,
                               u32 return_offset, u8 repeat_count, u8 loop_increment) {
             state.program_counter = &shader_memory[offset] - 1; // -1 to make sure when incrementing the PC we end up at the correct offset
-            state.call_stack.push({ offset + num_instructions, return_offset, repeat_count, loop_increment });
+            state.call_stack.push({ offset + num_instructions, return_offset, repeat_count, loop_increment, offset });
         };
         u32 binary_offset = state.program_counter - shader_memory.data();