qemu: command: Fix function name in comment

In commit 042c95bd qemuBuildStorageSourceChainAttachPrepareBlockdev
was added but the comment for the function mentions
qemuBuildStorageSourceChainAttachPrepareDrive. Fix the mistake.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/qemu/qemu_command.c

@@ -11160,7 +11160,7 @@ qemuBuildStorageSourceChainAttachPrepareDrive(virDomainDiskDefPtr disk,
 
 
 /**
- * qemuBuildStorageSourceChainAttachPrepareDrive:
+ * qemuBuildStorageSourceChainAttachPrepareBlockdev:
  * @top: storage source chain
  * @qemuCaps: qemu capabilities object
  *