uio driver: apply style changes suggested by checkpatch.pl

Signed-off-by: Henning Schild <henning.schild@siemens.com>
uio tests: remove cmake generated Makefile

Signed-off-by: Henning Schild <henning.schild@siemens.com>
gitignore: ignore build output of uio interrupt tests

Signed-off-by: Henning Schild <henning.schild@siemens.com>
uio driver: fix error handling in probe and cleanup in remove

Signed-off-by: Henning Schild <henning.schild@siemens.com>