staging: ccree: dma mask is type u64

The dma mask var was defined as dma_addr_t but should be
u64. This showed as a sparse warning when building for 32 bit.
Fix it by changing type to u64 and drop the cast.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>