testsuite: swap empty .gitignore for .gitkeep

Later commit will be removing some no longer needed .gitignore files
and/or contents.

In a few instances, we want the empty folder to be preserved so swap the
empty .gitignore for the more widely used and obvious (IMHO) .gitkeep.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Lucas De Marchi <demarchi@kernel.org>
Link: https://github.com/kmod-project/kmod/pull/pull/400
Signed-off-by: Lucas De Marchi <demarchi@kernel.org>

diff --git a/testsuite/rootfs-pristine/test-loaded/sys/module/btusb/holders/.gitignore b/testsuite/rootfs-pristine/test-loaded/sys/module/btusb/holders/.gitkeep
similarity index 100%
rename from testsuite/rootfs-pristine/test-loaded/sys/module/btusb/holders/.gitignore
rename to testsuite/rootfs-pristine/test-loaded/sys/module/btusb/holders/.gitkeep

diff --git a/testsuite/rootfs-pristine/test-rootfs/testdir/.gitignore b/testsuite/rootfs-pristine/test-rootfs/testdir/.gitkeep
similarity index 100%
rename from testsuite/rootfs-pristine/test-rootfs/testdir/.gitignore
rename to testsuite/rootfs-pristine/test-rootfs/testdir/.gitkeep