GenWQE: Accidently casting to u32 where u64 is required

Fix a casting to u32 where u64 would be appropriate.
The bad casting made the driver unusable.

Signed-off-by: Frank Haverkamp <haver@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>