libpayload: time: split time.h from libpayload.h

Move time functions and prototypes from libpayload.h to time.h.
In a similar manner to other c libary headers, this change makes
porting existing applications to libpayload easier.

Change-Id: I71e27c6dddde6e77e0e9b4d7be7cd5298e03a648
Signed-off-by: Stef van Os <stef.van.os@prodrive-technologies.com>
Reviewed-on: https://review.coreboot.org/14437
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

payloads/libpayload/include/libpayload.h

@@ -56,6 +56,7 @@
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
 #include <arch/types.h>
 #include <arch/io.h>
 #include <arch/virtual.h>
@@ -353,20 +354,6 @@ void SHA1Final(u8 digest[SHA1_DIGEST_LENGTH], SHA1_CTX *context);
 u8 *sha1(const u8 *data, size_t len, u8 *buf);
 /** @} */
 
-/**
- * @defgroup time Time functions
- * @{
- */
-
-/** System time structure */
-struct timeval {
-	time_t tv_sec;       /**< Seconds */
-	suseconds_t tv_usec; /**< Microseconds */
-};
-
-int gettimeofday(struct timeval *tv, void *tz);
-/** @} */
-
 /**
  * @defgroup info System information functions
  * This module contains functions that return information about the system