efi_loader: add efi_create_indexed_name()

This function will be used from several places in UEFI subsystem
to generate some specific form of utf-16 variable name.
For example, L"Capsule0001"

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Move function to separate module.
Use char * as argument instead of u16 *.
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
index 9bad1d1..8892fb0 100644
--- a/lib/efi_loader/Makefile
+++ b/lib/efi_loader/Makefile
@@ -34,6 +34,7 @@
 obj-y += efi_root_node.o
 obj-y += efi_runtime.o
 obj-y += efi_setup.o
+obj-y += efi_string.o
 obj-$(CONFIG_EFI_UNICODE_COLLATION_PROTOCOL2) += efi_unicode_collation.o
 obj-y += efi_var_common.o
 obj-y += efi_var_mem.o