[libc][NFC] Replace address space with constant GPU utility

Summary:
This was written before we had the address space helpers. Using
numerical address spaces is bad so this should be removed.

Author: jhuber6

libc/src/time/gpu/time_utils.cpp

@@ -15,8 +15,8 @@ namespace LIBC_NAMESPACE {
 // insufficient.
 // TODO: Once we have another use-case for this we should put it in a common
 // device environment struct.
-extern "C" [[gnu::visibility("protected")]] uint64_t
-    [[clang::address_space(4)]] __llvm_libc_clock_freq = clock_freq;
+extern "C" [[gnu::visibility("protected")]] gpu::Constant<uint64_t>
+    __llvm_libc_clock_freq = clock_freq;
 #endif
 
 } // namespace LIBC_NAMESPACE

libc/src/time/gpu/time_utils.h

@@ -23,8 +23,8 @@ constexpr uint64_t clock_freq = 100000000UL;
 
 // We provide an externally visible symbol such that the runtime can set
 // this to the correct value.
-extern "C" [[gnu::visibility("protected")]] uint64_t
-    [[clang::address_space(4)]] __llvm_libc_clock_freq;
+extern "C" [[gnu::visibility("protected")]] gpu::Constant<uint64_t>
+    __llvm_libc_clock_freq;
 #define GPU_CLOCKS_PER_SEC static_cast<clock_t>(__llvm_libc_clock_freq)
 
 #elif defined(LIBC_TARGET_ARCH_IS_NVPTX)