migration: Remove unused migrate_zero_blocks

migrate_zero_blocks is unused since
  eef0bae3a7 ("migration: Remove block migration")

Remove it.

Signed-off-by: Dr. David Alan Gilbert <dave@treblig.org>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20240919134626.166183-3-dave@treblig.org
Signed-off-by: Peter Xu <peterx@redhat.com>
diff --git a/migration/options.c b/migration/options.c
index 9460c5d..6f54998 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -339,13 +339,6 @@
     return s->capabilities[MIGRATION_CAPABILITY_XBZRLE];
 }
 
-bool migrate_zero_blocks(void)
-{
-    MigrationState *s = migrate_get_current();
-
-    return s->capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
-}
-
 bool migrate_zero_copy_send(void)
 {
     MigrationState *s = migrate_get_current();
diff --git a/migration/options.h b/migration/options.h
index 36e7b37..79084ee 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -40,7 +40,6 @@
 bool migrate_return_path(void);
 bool migrate_validate_uuid(void);
 bool migrate_xbzrle(void);
-bool migrate_zero_blocks(void);
 bool migrate_zero_copy_send(void);
 
 /*