fix(nxp-crypto): refine code to avoid hang issue for some of toolchain

bitfield structure maybe has strict-aliasing issue for some compiler,
for example the old code has hang issue for yocto 3.4 toolchain, so
refine the code to avoid to use bitfield structure.

Signed-off-by: Jiafei Pan <Jiafei.Pan@nxp.com>
Change-Id: I6b6d7597311240dd6d6b8ca4ce508c69332f9c68