Fix FIP offset address when file not found

If there is a request to open a file from FIP, and that file is not
found, the driver fails to reset the offset address. This causes
subsequent file loads to fail.

This patch resets the offset address to zero if a file is not found so
that subsequent file loads are unaffected.

Change-Id: I16418e35f92fb7c85fb12e2acc071990520cdef8

drivers/io/io_fip.c

@@ -298,6 +298,7 @@ static int fip_file_open(struct io_dev_info *dev_info, const void *spec,
 		entity->info = (uintptr_t)&current_file;
 	} else {
 		/* Did not find the file in the FIP. */
+		current_file.entry.offset_address = 0;
 		result = IO_FAIL;
 	}