test/hash: fix build

test/hash: fix build

Enable print_key_info() function compilation always.

Compilation error message:
'test_hash.c: In function ‘print_key_info’:
test_hash.c:90:15: error: cast discards ‘const’ qualifier from pointer
target type [-Werror=cast-qual]
  uint8_t *p = (uint8_t *)key;
               ^
cc1: all warnings being treated as errors'

Fixes: af75078fece36 ("first public release")
Cc: stable@dpdk.org
Suggested-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Signed-off-by: Dharmik Thakkar <dharmik.thakkar@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>