common: Move get_ticks() function out of common.h

This function belongs in time.h so move it over and add a comment.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/common/autoboot.c b/common/autoboot.c
index b28bd68..8faac20 100644
--- a/common/autoboot.c
+++ b/common/autoboot.c
@@ -15,6 +15,7 @@
 #include <memalign.h>
 #include <menu.h>
 #include <post.h>
+#include <time.h>
 #include <u-boot/sha256.h>
 #include <bootcount.h>
 
diff --git a/common/bootretry.c b/common/bootretry.c
index 47aaaa8..dac891f 100644
--- a/common/bootretry.c
+++ b/common/bootretry.c
@@ -9,6 +9,7 @@
 #include <cli.h>
 #include <env.h>
 #include <errno.h>
+#include <time.h>
 #include <watchdog.h>
 
 #ifndef CONFIG_BOOT_RETRY_MIN
diff --git a/common/cli_readline.c b/common/cli_readline.c
index ea510ed..6ef7a3e 100644
--- a/common/cli_readline.c
+++ b/common/cli_readline.c
@@ -11,6 +11,7 @@
 #include <common.h>
 #include <bootretry.h>
 #include <cli.h>
+#include <time.h>
 #include <watchdog.h>
 
 DECLARE_GLOBAL_DATA_PTR;
diff --git a/common/iotrace.c b/common/iotrace.c
index ba955af..295ee07 100644
--- a/common/iotrace.c
+++ b/common/iotrace.c
@@ -7,6 +7,7 @@
 
 #include <common.h>
 #include <mapmem.h>
+#include <time.h>
 #include <asm/io.h>
 #include <u-boot/crc.h>