efi_loader: rename Unicode collation protocol 2 variables

Rename variables to make it clear they refer to the Unicode collation
protocol identified by the EFI_UNICODE_PROTOCOL2_GUID.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 6501ee5..7e13ee5 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -36,14 +36,14 @@
 	  U-Boot implements enough of its features to be able to run the UEFI
 	  Shell, but not more than that.
 
-config EFI_UNICODE_COLLATION_PROTOCOL
+config EFI_UNICODE_COLLATION_PROTOCOL2
 	bool "Unicode collation protocol"
 	default y
 	help
 	  The Unicode collation protocol is used for lexical comparisons. It is
 	  required to run the UEFI shell.
 
-if EFI_UNICODE_COLLATION_PROTOCOL
+if EFI_UNICODE_COLLATION_PROTOCOL2
 
 config EFI_UNICODE_CAPITALIZATION
 	bool "Support Unicode capitalization"