Attn: Cleanup trace messages

Cleanup attention handler debug trace messages.

Signed-off-by: Ben Tyner <ben.tyner@ibm.com>
Change-Id: I2d5cc50e88c42278a37742ee361aec557ee15b28
diff --git a/attn/attn_handler.hpp b/attn/attn_handler.hpp
index 1500d39..d2b6764 100644
--- a/attn/attn_handler.hpp
+++ b/attn/attn_handler.hpp
@@ -14,6 +14,11 @@
     RC_CFAM_ERROR
 };
 
+/** @brief Attention global status bits */
+constexpr uint32_t SBE_ATTN       = 0x00000002;
+constexpr uint32_t CHECKSTOP_ATTN = 0x40000000;
+constexpr uint32_t SPECIAL_ATTN   = 0x20000000;
+
 /**
  * @brief The main attention handler logic
  *