spmi: Fix compilation error when CONFIG_PM_RUNTIME is defined

<linux/pm_runtime.h> should be included to fix any compilation errors
associated with enabling the PM_RUNTIME config.

Change-Id: Ided562e1351ccb5eef8957c305060275a5679d42
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>
diff --git a/drivers/spmi/spmi.c b/drivers/spmi/spmi.c
index 20a290a..f0cb924 100644
--- a/drivers/spmi/spmi.c
+++ b/drivers/spmi/spmi.c
@@ -19,7 +19,7 @@
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/spmi.h>
-
+#include <linux/pm_runtime.h>
 struct spmii_boardinfo {
 	struct list_head	list;
 	struct spmi_boardinfo	board_info;