fix: -Wsingle-bit-bitfield-constant-conversion with clang16

fix: -Wsingle-bit-bitfield-constant-conversion with clang16

We get the following warning with Clang 16:

  lttng-ust-abi.c:558:38: warning: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Wsingle-bit-bitfield-constant-conversion]
         lttng_chan_buf->priv->parent.tstate = 1;

My understanding is that there is no bug because we only check if the
values are zero or not, so we can silence the warning by making the
variables unsigned.

Change-Id: Ic4e02164d5adf4271fa24e5b13e5d320ae19de2e
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>