coresight: etm3x: Cleanup ETMTECR1 register accesses

This is a no-op change for style and consistency and has no effect on
the binary output by the compiler. These fields already have macros
to define them so use them instead of magic numbers.

Signed-off-by: James Clark <james.clark@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Link: https://lore.kernel.org/r/20220304171913.2292458-11-james.clark@arm.com


Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>