efi_loader: split unrelated code from efi_bootmgr.c

Some code moved from cmd/bootefi.c is actually necessary only for "bootefi
<addr>" command (starting an image manually loaded by a user using U-Boot
load commands or other methods (like JTAG debugger).

The code will never been opted out as unused code by a compiler which
doesn't know how EFI boot manager is implemented. So introduce a new
configuration, CONFIG_EFI_BINARY_EXEC, to enforce them opted out
explicitly.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
diff --git a/boot/Kconfig b/boot/Kconfig
index 0894ecf..70ff248 100644
--- a/boot/Kconfig
+++ b/boot/Kconfig
@@ -523,7 +523,7 @@
 
 config BOOTMETH_EFILOADER
 	bool "Bootdev support for EFI boot"
-	depends on BOOTEFI_BOOTMGR
+	depends on EFI_BINARY_EXEC
 	default y
 	help
 	  Enables support for EFI boot using bootdevs. This makes the
@@ -558,7 +558,7 @@
 	select BOOTMETH_SCRIPT if CMDLINE # E.g. Armbian uses scripts
 	select BOOTMETH_EXTLINUX  # E.g. Debian uses these
 	select BOOTMETH_EXTLINUX_PXE if CMD_PXE && CMD_NET && DM_ETH
-	select BOOTMETH_EFILOADER if BOOTEFI_BOOTMGR # E.g. Ubuntu uses this
+	select BOOTMETH_EFILOADER if EFI_BINARY_EXEC # E.g. Ubuntu uses this
 
 config SPL_BOOTMETH_VBE
 	bool "Bootdev support for Verified Boot for Embedded (SPL)"