jtag: linuxgpiod: drop extra parenthesis

Checkpatch complains for extra parenthesis not required.

Drop them.

Change-Id: I311409f5732acf10a4910de5dcf0fb05f43e21b5
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/8187


Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Tested-by: jenkins