To improve clarity, let's update the comment for etm4_os_unlock
to use the name of the register as per the ETM architecture
specification.

The existing comment is also misleading as it suggests any value
written to TRCOSLAR unlocks the trace registers, however it must
be '0' - let's also correct this.
Signed-off-by: NAndrew Murray <andrew.murray@arm.com>
Reviewed-by: NSuzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20190829202842.580-13-mathieu.poirier@linaro.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>