util: Promote shifted value in spdk_align64pow2 to uint64

Fix asan/valgrind error when using spdk_align64pow2 with >=32b values.

Signed-off-by: Mateusz Kozlowski <mateusz.kozlowski@intel.com>
Change-Id: I326a32a01a5b8b5ee9b10693900a60c50ee8f900
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/471058


Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Wojciech Malikowski <wojciech.malikowski@intel.com>
Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com>