Convert CONFIG_SYS_SPL_MALLOC_SIZE et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_SPL_MALLOC_SIZE
   CONFIG_SYS_SPL_MALLOC_START

We introduce a default value here as well, and CONFIG_SYS_SPL_MALLOC to
control if we have a malloc pool or not.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/common/spl/spl.c b/common/spl/spl.c
index c8c463f..2a69a7c 100644
--- a/common/spl/spl.c
+++ b/common/spl/spl.c
@@ -19,6 +19,7 @@
 #include <mapmem.h>
 #include <serial.h>
 #include <spl.h>
+#include <system-constants.h>
 #include <asm/global_data.h>
 #include <asm-generic/gpio.h>
 #include <asm/u-boot.h>
@@ -728,9 +729,8 @@
 
 	spl_set_bd();
 
-#if defined(CONFIG_SYS_SPL_MALLOC_START)
-	mem_malloc_init(CONFIG_SYS_SPL_MALLOC_START,
-			CONFIG_SYS_SPL_MALLOC_SIZE);
+#if defined(CONFIG_SYS_SPL_MALLOC)
+	mem_malloc_init(SYS_SPL_MALLOC_START, CONFIG_SYS_SPL_MALLOC_SIZE);
 	gd->flags |= GD_FLG_FULL_MALLOC_INIT;
 #endif
 	if (!(gd->flags & GD_FLG_SPL_INIT)) {