[prim] Fix lint errors

Signed-off-by: Pirmin Vogel <vogelpi@lowrisc.org>

hw/ip/prim/rtl/prim_arbiter_ppc.sv

diff --git a/hw/ip/prim/rtl/prim_arbiter_ppc.sv b/hw/ip/prim/rtl/prim_arbiter_ppc.sv
index d72083a..298f2b9 100644
--- a/hw/ip/prim/rtl/prim_arbiter_ppc.sv
+++ b/hw/ip/prim/rtl/prim_arbiter_ppc.sv
@@ -28,7 +28,10 @@
 
   // Configurations
   // EnDataPort: {0, 1}, if 0, input data will be ignored
-  parameter int EnDataPort = 1
+  parameter int EnDataPort = 1,
+
+  // Derived parameters
+  localparam int unsigned IdxW = $clog2(N)
 ) (
   input clk_i,
   input rst_ni,
@@ -36,7 +39,7 @@
   input        [ N-1:0]        req_i,
   input        [DW-1:0]        data_i [N],
   output logic [ N-1:0]        gnt_o,
-  output logic [$clog2(N)-1:0] idx_o,
+  output logic [IdxW-1:0]      idx_o,
 
   output logic          valid_o,
   output logic [DW-1:0] data_o,
@@ -102,16 +105,16 @@
           end
         end
       end
-    end else begin
+    end else begin: gen_nodatapath
       assign data_o = '1;
       // TODO: waive data_i from NOT_READ error
     end
 
     always_comb begin
-      idx_o  = '0;
+      idx_o = '0;
       for (int i = 0 ; i < N ; i++) begin
         if (winner[i]) begin
-          idx_o  = i;
+          idx_o = i[IdxW-1:0];
         end
       end
     end

hw/ip/prim/rtl/prim_filter.sv

diff --git a/hw/ip/prim/rtl/prim_filter.sv b/hw/ip/prim/rtl/prim_filter.sv
index e582cce..214e0c3 100644
--- a/hw/ip/prim/rtl/prim_filter.sv
+++ b/hw/ip/prim/rtl/prim_filter.sv
@@ -20,6 +20,7 @@
 
   logic [Cycles-1:0] stored_vector_q, stored_vector_d;
   logic stored_value_q, update_stored_value;
+  logic unused_stored_vector_q_msb;
 
   always_ff @(posedge clk_i or negedge rst_ni) begin
     if (!rst_ni) begin
@@ -30,6 +31,7 @@
   end
 
   assign stored_vector_d = {stored_vector_q[Cycles-2:0],filter_i};
+  assign unused_stored_vector_q_msb = stored_vector_q[Cycles-1];
 
   always_ff @(posedge clk_i or negedge rst_ni) begin
     if (!rst_ni) begin