coresight: configure gpio on cti trigger map and unmap

Instead of configuring gpio on bootup, modify coresight cti
driver to allow configuring gpio when mapping or unmapping
cti trigin and trigout so that the gpio(s) are parked in a
functional state only when the mapping/use case is active
hence avoiding any potential power impact when not used.

Change-Id: I375253843210d3873d443e1da195c86927698167
Signed-off-by: Aparna Das <adas@codeaurora.org>