attn: Add support for hbNotVisibleFlag in TI info

Hostboot defined a new flag in the TI info data. This flag is used to
indicate to the attention handler that a PEL created by attention
handler for a TI with SRC event should have the hidden-flag set in the
action flags.

Signed-off-by: Ben Tyner <ben.tyner@ibm.com>
Change-Id: I8090085274635109510e1af0513b39afa994781b
diff --git a/attn/pel/pel_common.hpp b/attn/pel/pel_common.hpp
index 3dbce5c..1d99015 100644
--- a/attn/pel/pel_common.hpp
+++ b/attn/pel/pel_common.hpp
@@ -49,6 +49,7 @@
 enum class ActionFlags
 {
     service = 0x8000,
+    hidden  = 0x4000,
     report  = 0x2000,
     call    = 0x0800
 };