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_block_device.c b/lib/efi_selftest/efi_selftest_block_device.c
index 29ac0ce..644c5ad 100644
--- a/lib/efi_selftest/efi_selftest_block_device.c
+++ b/lib/efi_selftest/efi_selftest_block_device.c
@@ -337,7 +337,7 @@
 		}
 		if (len >= dp_size(dp_partition))
 			continue;
-		if (efi_st_memcmp(dp, dp_partition, len))
+		if (memcmp(dp, dp_partition, len))
 			continue;
 		handle_partition = handles[i];
 		break;
@@ -409,7 +409,7 @@
 			     (unsigned int)buf_size);
 		return EFI_ST_FAILURE;
 	}
-	if (efi_st_memcmp(buf, "ello world!", 11)) {
+	if (memcmp(buf, "ello world!", 11)) {
 		efi_st_error("Unexpected file content\n");
 		return EFI_ST_FAILURE;
 	}
@@ -480,7 +480,7 @@
 			     (unsigned int)buf_size);
 		return EFI_ST_FAILURE;
 	}
-	if (efi_st_memcmp(buf, "U-Boot", 7)) {
+	if (memcmp(buf, "U-Boot", 7)) {
 		efi_st_error("Unexpected file content %s\n", buf);
 		return EFI_ST_FAILURE;
 	}