When compiling with android toolchain, there is an instruction
"str q0, [x8],#16", but x8 is not 16bytes aligned,
this instruction will trigger sync abort.
So, following Linux kernel, only use general regs option to IMX8 and
IMX8M aarch64 only.
If not, compiler may use simd registers Q[x]. We need to avoid
using simd registers in U-Boot, because load/store Q[x] has
restriction that 128bits aligned when str/ldr.