metag: OProfile support

Add OProfile support for metag, using the perf backend, and falling back
to generic timer based sampling if perf counter interrupt support is
disabled.

The oprofile code prepends "metag/" to the perf pmu name to give
"metag/meta2" which is more consistent with other oprofile arch names.

The backtrace code makes use of <asm/stacktrace.h> for kernel
backtracing, and a simple frame pointer walk for userland backtracing.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Robert Richter <rric@kernel.org>
Cc: oprofile-list@lists.sf.net
diff --git a/arch/metag/Makefile b/arch/metag/Makefile
index 81bd6a1..b566116 100644
--- a/arch/metag/Makefile
+++ b/arch/metag/Makefile
@@ -49,6 +49,8 @@
 libs-y					+= arch/metag/lib/
 libs-y					+= arch/metag/tbx/
 
+drivers-$(CONFIG_OPROFILE)		+= arch/metag/oprofile/
+
 boot					:= arch/metag/boot
 
 boot_targets				+= uImage