Make export interface support CONFIG_SYS_MALLOC_SIMPLE

When CONFIG_SYS_MALLOC_SIMPLE is defined, free() is a static inline. Make
sure that the export interface still builds in this case.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/_exports.h

@@ -23,7 +23,9 @@
 	EXPORT_FUNC(dummy, void, free_hdlr, void)
 #endif
 	EXPORT_FUNC(malloc, void *, malloc, size_t)
+#ifndef CONFIG_SYS_MALLOC_SIMPLE
 	EXPORT_FUNC(free, void, free, void *)
+#endif
 	EXPORT_FUNC(udelay, void, udelay, unsigned long)
 	EXPORT_FUNC(get_timer, unsigned long, get_timer, unsigned long)
 	EXPORT_FUNC(vprintf, int, vprintf, const char *, va_list)

include/exports.h

@@ -15,7 +15,9 @@ int printf(const char* fmt, ...);
 void install_hdlr(int, interrupt_handler_t, void*);
 void free_hdlr(int);
 void *malloc(size_t);
+#ifndef CONFIG_SYS_MALLOC_SIMPLE
 void free(void*);
+#endif
 void __udelay(unsigned long);
 unsigned long get_timer(unsigned long);
 int vprintf(const char *, va_list);