delloem: Fix the unalign bug in arm64

For computers using the arm64 of the Apple chip, the link requires strict
alignment of pointers in 32-bit form. Replace the struct vFlashstr to valstr.
Replace the Function get_vFlash_compcode_str to val2str.

Resolves ipmitool/ipmitool#332
Signed-off-by: SliderLu <314238828@qq.com>