coresight: cti-sysfs: Re-use same functions for similar sysfs register accessors

Currently each accessor macro creates an identical function which
wastes space in the text area and pollutes the ftrace function
name list. Change it so that the same function is used, but the register
to access is passed in as parameter rather than baked into each
function.

Signed-off-by: James Clark <james.clark@arm.com>