test: spl: Remove usage of FAT32_SIGN

FAT32_SIGN is removed in the following commits.

Signed-off-by: Christian Taedcke <christian.taedcke@weidmueller.com>
diff --git a/test/image/spl_load_fs.c b/test/image/spl_load_fs.c
index 297ab08..90e640b 100644
--- a/test/image/spl_load_fs.c
+++ b/test/image/spl_load_fs.c
@@ -220,7 +220,7 @@
 	bs->root_cluster = cpu_to_le32(root_sector);
 
 	vi->ext_boot_sign = 0x29;
-	memcpy(vi->fs_type, FAT32_SIGN, sizeof(vi->fs_type));
+	memcpy(vi->fs_type, "FAT32   ", sizeof(vi->fs_type));
 
 	memcpy(dst + 0x1fe, "\x55\xAA", 2);