UPSTREAM: coresight: Fix check in coresight_tmc_etr_buf_insert_barrier_packet

We request for "CORESIGHT_BARRIER_PKT_SIZE" length and we should
be happy when we get that size.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

(Upstream commit 00ea1970298677e31ed8f962bda663cfc4848481).

Bug: 140266694
Change-Id: Ib850da4881b95b9610ac8d9d115fd20b514f94ea
Signed-off-by: Yabin Cui <yabinc@google.com>