char: xilinx_hwicap: drop casting to void in dev_set_drvdata

The C standard specifies that there is no need to cast from a pointer to
void [1]. Therefore, it can be safely dropped.

[1] C Standard Committee: https://c0x.shape-of-code.com/6.3.2.3.html

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20240303-void_in_dev_set_drvdata-v1-1-ae39027d740b@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>