bootmeth: use efi_loader interfaces instead of bootefi command

Now that efi_loader subsystem provides interfaces that are equivalent
with bootefi command, we can replace command invocations with APIs.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
diff --git a/boot/Makefile b/boot/Makefile
index de0eafe..a90ebea 100644
--- a/boot/Makefile
+++ b/boot/Makefile
@@ -34,7 +34,7 @@
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_SANDBOX) += bootmeth_sandbox.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_SCRIPT) += bootmeth_script.o
 ifdef CONFIG_$(SPL_TPL_)BOOTSTD_FULL
-obj-$(CONFIG_CMD_BOOTEFI_BOOTMGR) += bootmeth_efi_mgr.o
+obj-$(CONFIG_BOOTEFI_BOOTMGR) += bootmeth_efi_mgr.o
 obj-$(CONFIG_$(SPL_TPL_)EXPO) += bootflow_menu.o
 obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += bootflow_menu.o
 obj-$(CONFIG_$(SPL_TPL_)CEDIT) += cedit.o