coresight: Move all sysfs code to sysfs file

coresight: Move all sysfs code to sysfs file

At the moment the core file contains both sysfs functionality and
core functionality, while the Perf mode is in a separate file in
coresight-etm-perf.c

Many of the functions have ambiguous names like
coresight_enable_source() which actually only work in relation to the
sysfs mode. To avoid further confusion, move everything that isn't core
functionality into the sysfs file and append  _sysfs to the ambiguous
functions.

Signed-off-by: James Clark <james.clark@arm.com>
Link: https://lore.kernel.org/r/20240129154050.569566-7-james.clark@arm.com
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>