efi_selftest: remove redundant function efi_st_memcmp()

Function memcmp() is available in efi_freestanding.c. So we do not remove a
further implementation.

Replace all usages of efi_st_memcmp() by memcmp().

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_selftest/efi_selftest_loadimage.c b/lib/efi_selftest/efi_selftest_loadimage.c
index 449b6bf..06a87df 100644
--- a/lib/efi_selftest/efi_selftest_loadimage.c
+++ b/lib/efi_selftest/efi_selftest_loadimage.c
@@ -322,8 +322,7 @@
 	 efi_uintn_t *buffer_size, void *buffer)
 {
 	if (this == &file) {
-		if (efi_st_memcmp(info_type, &guid_file_info,
-				  sizeof(efi_guid_t)))
+		if (memcmp(info_type, &guid_file_info, sizeof(efi_guid_t)))
 			return EFI_INVALID_PARAMETER;
 		if (*buffer_size >= sizeof(struct file_info)) {
 			boottime->copy_mem(buffer, file_info,
@@ -333,8 +332,8 @@
 			return EFI_BUFFER_TOO_SMALL;
 		}
 	} else if (this == &volume) {
-		if (efi_st_memcmp(info_type, &guid_file_system_info,
-				  sizeof(efi_guid_t)))
+		if (memcmp(info_type, &guid_file_system_info,
+			   sizeof(efi_guid_t)))
 			return EFI_INVALID_PARAMETER;
 		if (*buffer_size >= sizeof(struct file_system_info)) {
 			boottime->copy_mem(buffer, file_system_info,