Remove @brief commands from doxygen comments, too.

This is a follow-up to r331272.

We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.

Patch produced by
  for i in $(git grep -l '\@brief'); do perl -pi -e 's/\@brief //g' $i & done

https://reviews.llvm.org/D46290

llvm-svn: 331275
diff --git a/llvm/lib/Target/AMDGPU/AMDKernelCodeT.h b/llvm/lib/Target/AMDGPU/AMDKernelCodeT.h
index df70a9f..289642a 100644
--- a/llvm/lib/Target/AMDGPU/AMDKernelCodeT.h
+++ b/llvm/lib/Target/AMDGPU/AMDKernelCodeT.h
@@ -198,7 +198,7 @@
   AMD_CODE_PROPERTY_RESERVED2 = ((1 << AMD_CODE_PROPERTY_RESERVED2_WIDTH) - 1) << AMD_CODE_PROPERTY_RESERVED2_SHIFT
 };
 
-/// @brief The hsa_ext_control_directives_t specifies the values for the HSAIL
+/// The hsa_ext_control_directives_t specifies the values for the HSAIL
 /// control directives. These control how the finalizer generates code. This
 /// struct is used both as an argument to hsaFinalizeKernel to specify values for
 /// the control directives, and is used in HsaKernelCode to record the values of