uio_pdrv_genirq: Remove warning when irq is not specified

commit 324ac45f upstream.

Since e3a3c3a2 ("UIO: fix uio_pdrv_genirq with device tree but no
interrupt"), the uio_pdrv_genirq has supported use without interrupt,
so the change in 7723f4c5 ("driver core: platform: Add an error
message to") added false warnings for those cases.

Fixes: 7723f4c5

 ("driver core: platform: Add an error message to platform_get_irq*()")
Signed-off-by: Esben Haabendal <esben@geanix.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200701145659.3978-2-esben@geanix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>