LU-16217 iokit: update .gitignore files

LU-16217 iokit: update .gitignore files

Add missing .gitignore file to new iokit directory.

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I4d292c26971f4bd805dc0f2a35e4a281646405ee
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50594
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Alexey Lyashkov <alexey.lyashkov@hpe.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>