[dv] Cleanup lint warnings in chip_env_pkg

Signed-off-by: Srikrishna Iyer <sriyer@google.com>
diff --git a/hw/top_earlgrey/dv/env/chip_env_pkg.sv b/hw/top_earlgrey/dv/env/chip_env_pkg.sv
index 186cbee..98152be 100644
--- a/hw/top_earlgrey/dv/env/chip_env_pkg.sv
+++ b/hw/top_earlgrey/dv/env/chip_env_pkg.sv
@@ -23,7 +23,7 @@
   `include "dv_macros.svh"
 
   // local parameters and types
-  parameter NUM_GPIOS = 16;
+  parameter uint NUM_GPIOS = 16;
 
   // SW constants
   parameter bit [TL_AW-1:0] SW_DV_LOG_ADDR = 32'h1000fffc;