refactor(bl31): use elx_panic for sysreg_handler64

When we reach sysreg_handler64 from any trap handling we are entering
this path from lower EL and thus we should be calling lower_el_panic
reporting mechanism to print panic report.

Make report_elx_panic available through assembly func elx_panic which
could be used for reporting any lower_el_panic.

Change-Id: Ieb260cf20ea327a59db84198b2c6a6bfc9ca9537
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/include/common/debug.h b/include/common/debug.h
index e0b3a1c..5ea541d 100644
--- a/include/common/debug.h
+++ b/include/common/debug.h
@@ -100,7 +100,7 @@
 #endif
 
 void __dead2 el3_panic(void);
-void __dead2 report_elx_panic(void);
+void __dead2 elx_panic(void);
 
 #define panic()				\
 	do {				\
@@ -118,7 +118,7 @@
 #define	lower_el_panic()		\
 	do {				\
 		console_flush();	\
-		report_elx_panic();	\
+		elx_panic();		\
 	} while (false)
 #else
 #define	lower_el_panic()