efi_loader: efi_set_variable use const void *

The SetVariable() runtime service does not change the data passed to it.
So mark the parameter as constant.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/include/efi_api.h b/include/efi_api.h
index 83fd12b..1d37747 100644
--- a/include/efi_api.h
+++ b/include/efi_api.h
@@ -230,7 +230,8 @@
 	efi_status_t (EFIAPI *set_variable)(u16 *variable_name,
 					    const efi_guid_t *vendor,
 					    u32 attributes,
-					    efi_uintn_t data_size, void *data);
+					    efi_uintn_t data_size,
+					    const void *data);
 	efi_status_t (EFIAPI *get_next_high_mono_count)(
 			uint32_t *high_count);
 	void (EFIAPI *reset_system)(enum efi_reset_type reset_type,
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 5420c99..b446781 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -518,7 +518,7 @@
 					       const efi_guid_t *vendor);
 efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
 				     const efi_guid_t *vendor, u32 attributes,
-				     efi_uintn_t data_size, void *data);
+				     efi_uintn_t data_size, const void *data);
 
 /*
  * See section 3.1.3 in the v2.7 UEFI spec for more details on
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index 4e6a04e..c302dbd 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -254,7 +254,7 @@
 /* http://wiki.phoenix.com/wiki/index.php/EFI_RUNTIME_SERVICES#SetVariable.28.29 */
 efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
 				     const efi_guid_t *vendor, u32 attributes,
-				     efi_uintn_t data_size, void *data)
+				     efi_uintn_t data_size, const void *data)
 {
 	char *native_name = NULL, *val = NULL, *s;
 	efi_status_t ret = EFI_SUCCESS;