queries: fix partially-uninitialized struct

[schopin-pro]

The x instance wasn't initialized properly, which led to undefined behaviour in _tgl_do_send_photo when copying its content to t->avatar.

This patch fixes that by using the C struct initializer syntax, which implicitly sets all missing fields to 0.

Note that this UB triggers a compilation warning when compiling with recent GCC versions in -O3.