staging: unisys: Solve sparse warning

The following commit fixes the following sparse report:

drivers/staging//unisys/visorhba/visorhba_main.c:660:29: warning: cast to restricted __le64

by casting readq (which is unsigned long on x86) to u64, as expected by the seq_printf call.

Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>
Acked-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>