ftrace: have function graph use mcount caller address

Impact: consistency change for function graph

This patch makes function graph record the mcount caller address
the same way the function tracer does.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 958af86..826682a 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1230,6 +1230,7 @@
 	pushl %edx
 	movl 0xc(%esp), %edx
 	lea 0x4(%ebp), %eax
+	subl $MCOUNT_INSN_SIZE, %edx
 	call prepare_ftrace_return
 	popl %edx
 	popl %ecx