Add missing __device__ for forward declares.

[ROCm/clr commit: 13a1917741]

projects/clr/hipamd/include/hip/hcc_detail/hip_atomic.h

@@ -176,7 +176,9 @@ __device__
 inline
 unsigned int atomicInc(unsigned int* address, unsigned int val)
 {
-    extern unsigned int __builtin_amdgcn_atomic_inc(
+    __device__
+    extern 
+    unsigned int __builtin_amdgcn_atomic_inc(
         unsigned int*,
         unsigned int,
         unsigned int,
@@ -191,7 +193,9 @@ __device__
 inline
 unsigned int atomicDec(unsigned int* address, unsigned int val)
 {
-    extern unsigned int __builtin_amdgcn_atomic_dec(
+    __device__
+    extern 
+    unsigned int __builtin_amdgcn_atomic_dec(
         unsigned int*,
         unsigned int,
         unsigned int,
@@ -262,4 +266,4 @@ unsigned long long atomicXor(
     return __atomic_fetch_xor(address, val, __ATOMIC_RELAXED);
 }
 
-// TODO: add scoped atomics i.e. atomic{*}_system && atomic{*}_block.
+// TODO: add scoped atomics i.e. atomic{*}_system && atomic{*}_block.