efi: Use 16-bit unicode strings

At present we use wide characters for unicode but this is not necessary.
Change the code to use the 'u' literal instead. This helps to fix build
warnings for sandbox on rpi.

Signed-off-by: Simon Glass <sjg@chromium.org>
Suggested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
index 380adc1..eee54e4 100644
--- a/lib/efi_loader/efi_setup.c
+++ b/lib/efi_loader/efi_setup.c
@@ -43,7 +43,7 @@
 	 * Variable PlatformLangCodes defines the language codes that the
 	 * machine can support.
 	 */
-	ret = efi_set_variable_int(L"PlatformLangCodes",
+	ret = efi_set_variable_int(u"PlatformLangCodes",
 				   &efi_global_variable_guid,
 				   EFI_VARIABLE_BOOTSERVICE_ACCESS |
 				   EFI_VARIABLE_RUNTIME_ACCESS |
@@ -57,7 +57,7 @@
 	 * Variable PlatformLang defines the language that the machine has been
 	 * configured for.
 	 */
-	ret = efi_get_variable_int(L"PlatformLang",
+	ret = efi_get_variable_int(u"PlatformLang",
 				   &efi_global_variable_guid,
 				   NULL, &data_size, &pos, NULL);
 	if (ret == EFI_BUFFER_TOO_SMALL) {
@@ -74,7 +74,7 @@
 	if (pos)
 		*pos = 0;
 
-	ret = efi_set_variable_int(L"PlatformLang",
+	ret = efi_set_variable_int(u"PlatformLang",
 				   &efi_global_variable_guid,
 				   EFI_VARIABLE_NON_VOLATILE |
 				   EFI_VARIABLE_BOOTSERVICE_ACCESS |
@@ -100,7 +100,7 @@
 	};
 	efi_status_t ret;
 
-	ret = efi_set_variable_int(L"SignatureSupport",
+	ret = efi_set_variable_int(u"SignatureSupport",
 				   &efi_global_variable_guid,
 				   EFI_VARIABLE_READ_ONLY |
 				   EFI_VARIABLE_BOOTSERVICE_ACCESS |
@@ -129,12 +129,12 @@
 	efi_status_t ret = EFI_SUCCESS;
 
 	if (IS_ENABLED(CONFIG_EFI_HAVE_CAPSULE_UPDATE)) {
-		ret = efi_set_variable_int(L"CapsuleMax",
+		ret = efi_set_variable_int(u"CapsuleMax",
 					   &efi_guid_capsule_report,
 					   EFI_VARIABLE_READ_ONLY |
 					   EFI_VARIABLE_BOOTSERVICE_ACCESS |
 					   EFI_VARIABLE_RUNTIME_ACCESS,
-					   22, L"CapsuleFFFF", false);
+					   22, u"CapsuleFFFF", false);
 		if (ret != EFI_SUCCESS)
 			printf("EFI: cannot initialize CapsuleMax variable\n");
 	}
@@ -165,7 +165,7 @@
 		os_indications_supported |=
 			EFI_OS_INDICATIONS_FMP_CAPSULE_SUPPORTED;
 
-	return efi_set_variable_int(L"OsIndicationsSupported",
+	return efi_set_variable_int(u"OsIndicationsSupported",
 				    &efi_global_variable_guid,
 				    EFI_VARIABLE_BOOTSERVICE_ACCESS |
 				    EFI_VARIABLE_RUNTIME_ACCESS |