crypto: aspeed: fix format unexpected build warning

This fixes the following similar build warning when
enabling compile test:

aspeed-hace-hash.c:188:9: warning: format '%x' expects argument of type
'unsigned int', but argument 7 has type 'size_t' {aka 'long unsigned int'}
[-Wformat=]

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Neal Liu <neal_liu@aspeedtech.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>