Revert "microblaze: UIO setup compatible property"

This reverts commit 3976b667.

This patch removes "generic-uio" compatible string from the driver.
This hack is in our tree for a long time and it is time
to fix it. For ensuring the same behaviour please add
uio_pdrv_genirq.of_id="generic-uio" to bootargs.

Feel free to use different compatible string for your purpose.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>