Fix unit test warnings

These result in unsigned to signed comparisons that gtest and gcc in
some configurations warns on.  Fix the literals to be unsigned.

Change-Id: I63e522ddefb4bf3a97c1e7b2f3c48b159f03ae1f
Signed-off-by: Ed Tanous <etanous@nvidia.com>
diff --git a/src/nvidia-gpu/tests/NvidiaGpuSensorTest.cpp b/src/nvidia-gpu/tests/NvidiaGpuSensorTest.cpp
index d293ca5..436a5f7 100644
--- a/src/nvidia-gpu/tests/NvidiaGpuSensorTest.cpp
+++ b/src/nvidia-gpu/tests/NvidiaGpuSensorTest.cpp
@@ -719,7 +719,7 @@
     EXPECT_EQ(result, 0);
     EXPECT_EQ(cc, ocp::accelerator_management::CompletionCode::SUCCESS);
     EXPECT_EQ(reasonCode, 0);
-    EXPECT_EQ(power, 250);
+    EXPECT_EQ(power, 250U);
 }
 
 TEST_F(GpuMctpVdmTests, DecodeGetCurrentPowerDrawResponseError)
@@ -871,7 +871,7 @@
     EXPECT_EQ(result, 0);
     EXPECT_EQ(cc, ocp::accelerator_management::CompletionCode::SUCCESS);
     EXPECT_EQ(reasonCode, 0);
-    EXPECT_EQ(energy, 3600000);
+    EXPECT_EQ(energy, 3600000U);
 }
 
 TEST_F(GpuMctpVdmTests, DecodeGetCurrentEnergyCounterResponseError)
@@ -1020,7 +1020,7 @@
     EXPECT_EQ(result, 0);
     EXPECT_EQ(cc, ocp::accelerator_management::CompletionCode::SUCCESS);
     EXPECT_EQ(reasonCode, 0);
-    EXPECT_EQ(voltage, 12500);
+    EXPECT_EQ(voltage, 12500U);
 }
 
 TEST_F(GpuMctpVdmTests, DecodeGetVoltageResponseError)