In the I2S CAVS driver, the DMA user data simply points to
the device struct. However, after the change to const-ify device
struct, this causes warnings from compiler because the user_data
assignment would discard the const qualifier. The user_data is
being used to point back to the device struct, and the DMA
callbacks are already casting the user data argument into
a const device struct. So it's a simple fix by casting
the device pointer to void pointer at device creation.
Fixes#28016
Signed-off-by: Daniel Leung <daniel.leung@intel.com>