UPSTREAM: coresight tmc etr: Fix uninitialised variable

Variable 'paddr' can't be used if uninitialised but is nonetheless
confusing to some static checker.  As such simply initialise it to zero.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

(Upstream commit 805c2c2cd0d3f16438d2391f3f188e4357fbc1cc).

Bug: 140266694
Change-Id: Ibb50e47ecf46106879ccae7117f0c3745b6c0685
Signed-off-by: Yabin Cui <yabinc@google.com>