libpayload: Make Kconfig bools use IS_ENABLED()

This will make the code work with the different styles
of Kconfig (emit unset bools vs don't emit unset bools)

Roughly, the patch does this, and a little bit of fixing up:

perl -pi -e 's,ifdef (CONFIG_LP_.+?)\b,if IS_ENABLED\($1\),g' `find . -name *.[ch]`
perl -pi -e 's,ifndef (CONFIG_LP_.+?)\b,if !IS_ENABLED\($1\),g' `find . -name *.[ch]`

Change-Id: Ib8a839b056a1f806a8597052e1b571ea3d18a79f
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/10711
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

payloads/libpayload/include/stdlib.h

@@ -45,7 +45,7 @@
  * @defgroup malloc Memory allocation functions
  * @{
  */
-#if defined(CONFIG_LP_DEBUG_MALLOC) && !defined(IN_MALLOC_C)
+#if IS_ENABLED(CONFIG_LP_DEBUG_MALLOC) && !defined(IN_MALLOC_C)
 #define free(p)	\
 	({ \
 	 extern void print_malloc_map(void); \
@@ -217,7 +217,7 @@ void srand(unsigned int seed);
 void halt(void) __attribute__ ((noreturn));
 void exit(int status) __attribute__ ((noreturn));
 #define abort() halt()    /**< Alias for the halt() function */
-#ifdef CONFIG_LP_REMOTEGDB
+#if IS_ENABLED(CONFIG_LP_REMOTEGDB)
 /* Override abort()/halt() to trap into GDB if it is enabled. */
 #define halt() do { gdb_enter(); halt(); } while (0)
 #endif