Fix a memleak in the dummyflasher

Emu_persistent_image was not freed correctly.

This bug was found thanks to valgrind.

Corresponding to flashrom svn r1603.
Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>

dummyflasher.c

@@ -150,8 +150,9 @@ static int dummy_shutdown(void *data)
 	if (emu_chip != EMULATE_NONE) {
 		if (emu_persistent_image) {
 			msg_pdbg("Writing %s\n", emu_persistent_image);
-			write_buf_to_file(flashchip_contents, emu_chip_size,
-					  emu_persistent_image);
+			write_buf_to_file(flashchip_contents, emu_chip_size, emu_persistent_image);
+			free(emu_persistent_image);
+			emu_persistent_image = NULL;
 		}
 		free(flashchip_contents);
 	}