Remove unused function from es31fSRGBDecodeTests.cpp

Unused function causes compiler warnings to appear with recent GCC
versions.

Change-Id: I941c579994acbc9146df86acf5b9da9ee85341f5
(cherry picked from commit 1ee59ff98641dc0be7511e03e37b5843ff7eed82)
diff --git a/modules/gles31/functional/es31fSRGBDecodeTests.cpp b/modules/gles31/functional/es31fSRGBDecodeTests.cpp
index 1f4e49a..9a6cdf4 100644
--- a/modules/gles31/functional/es31fSRGBDecodeTests.cpp
+++ b/modules/gles31/functional/es31fSRGBDecodeTests.cpp
@@ -588,7 +588,6 @@
 	void							setUniformToggle		(int location, bool toggleDecodeValue);
 
 	const std::vector<UniformData>&	getUniformDataList		(void) const;
-	const UniformData&				getUniformAtLocation	(int location) const;
 	int								getUniformLocation		(const std::string& name);
 	deUint32						getHandle				(void) const;
 	bool							getBlendRequired		(void) const;
@@ -698,11 +697,6 @@
 	return m_uniformDataList;
 }
 
-const UniformData& SRGBTestProgram::getUniformAtLocation (int location) const
-{
-	return m_uniformDataList[location];
-}
-
 int SRGBTestProgram::getUniformLocation (const std::string& name)
 {
 	for (std::size_t idx = 0; idx < m_uniformDataList.size(); idx++)