efi_loader: rename BOOTEFI_BOOTMGR to EFI_BOOTMGR

At this point, EFI boot manager interfaces is fully independent from
bootefi command. So just rename the configuration parameter.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/test/boot/bootflow.c b/test/boot/bootflow.c
index 104f49d..fa54dde 100644
--- a/test/boot/bootflow.c
+++ b/test/boot/bootflow.c
@@ -374,7 +374,7 @@
 {
 	struct udevice *bootstd, *dev;
 
-	if (!IS_ENABLED(CONFIG_BOOTEFI_BOOTMGR))
+	if (!IS_ENABLED(CONFIG_EFI_BOOTMGR))
 		return -EAGAIN;
 	ut_assertok(uclass_first_device_err(UCLASS_BOOTSTD, &bootstd));
 	ut_assertok(device_bind(bootstd, DM_DRIVER_GET(bootmeth_efi_mgr),