io_uring: Rename KConfig to Kconfig

Kconfig files are traditionally named "Kconfig".

Fixes: 6f377873 ("io_uring/zcrx: add interface queue and refill queue")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/5ae387c1465f54768b51a5a1ca87be7934c4b2ad.1739976387.git.geert+renesas@glider.be


Signed-off-by: Jens Axboe <axboe@kernel.dk>