NFC: trf7970a: Cancel timer when error encountered

Some paths leave a timer still running when
trf7970a_send_err_upstream() is called.  This
can cause a timeout to occur in a subsequent
transaction making it fail.  Fix this by ensuring
there is no timer running before sending an error
upstream.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>