fs_mgr: Track the bootloader_message struct change.

A/B-specific info (slot_suffix) has been moved into struct
bootloader_message_ab.

Bug: 29193360
Change-Id: Ic655e23a2d74366e713807add15a6e9d04535cf5
diff --git a/fs_mgr/fs_mgr_slotselect.c b/fs_mgr/fs_mgr_slotselect.c
index ca07b18..0f59115 100644
--- a/fs_mgr/fs_mgr_slotselect.c
+++ b/fs_mgr/fs_mgr_slotselect.c
@@ -41,7 +41,7 @@
     int n;
     int misc_fd;
     ssize_t num_read;
-    struct bootloader_message msg;
+    struct bootloader_message_ab msg;
 
     misc_fd = -1;
     for (n = 0; n < fstab->num_entries; n++) {