sandbox: bootm: Enable more bootm OS methods

It is useful for sandbox to build as much code as possible. Enable
support for booting various other operating systems. Add the missing
cache functions.

These operating systems do not actually boot on sandbox, of course.

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

arch/sandbox/cpu/cpu.c

@@ -286,6 +286,14 @@ void sandbox_set_enable_pci_map(int enable)
 	enable_pci_map = enable;
 }
 
+void dcache_enable(void)
+{
+}
+
+void dcache_disable(void)
+{
+}
+
 int dcache_status(void)
 {
 	return 1;

configs/sandbox_defconfig

@@ -44,10 +44,11 @@ CONFIG_CMD_CPU=y
 CONFIG_CMD_LICENSE=y
 CONFIG_CMD_BOOTM_PRE_LOAD=y
 CONFIG_CMD_BOOTZ=y
+CONFIG_BOOTM_OPENRTOS=y
+CONFIG_BOOTM_OSE=y
 CONFIG_CMD_BOOTEFI_HELLO=y
 CONFIG_CMD_BOOTMENU=y
 CONFIG_CMD_ABOOTIMG=y
-# CONFIG_CMD_ELF is not set
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_GREPENV=y
 CONFIG_CMD_ERASEENV=y