oprofile: Adding switch counter to oprofile statistic variables

This patch moves the multiplexing switch counter from x86 code to
common oprofile statistic variables. Now the value will be available
and usable for all architectures. The initialization and
incrementation also moved to common code.

Signed-off-by: Robert Richter <robert.richter@amd.com>
diff --git a/drivers/oprofile/oprofile_stats.h b/drivers/oprofile/oprofile_stats.h
index 3da0d08..0b54e46 100644
--- a/drivers/oprofile/oprofile_stats.h
+++ b/drivers/oprofile/oprofile_stats.h
@@ -17,6 +17,7 @@
 	atomic_t sample_lost_no_mapping;
 	atomic_t bt_lost_no_mapping;
 	atomic_t event_lost_overflow;
+	atomic_t multiplex_counter;
 };
 
 extern struct oprofile_stat_struct oprofile_stats;