crypto/fsl: fix unaligned access

crypto/fsl: fix unaligned access

On aarch64 running with dcache off, will result in an unaligned access
exception:

   => dcache off
   => hash sha1 $kernel_addr_r 100
   "Synchronous Abort" handler, esr 0x96000061
   elr: 00000000960317d8 lr : 00000000960316a4 (reloc)
   elr: 00000000fbd787d8 lr : 00000000fbd786a4
   [..]

The compiler emits a "stur x1, [x0, #12]". x1 is might just be 32 bit
aligned pointer. Remove the unused u64 element from the union to drop
the minimal alignment to 32 bit. Also remove the union, because it is
no more needed.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>