MdePkg HobLib: Check FV alignment when building FV HOB

MdePkg HobLib: Check FV alignment when building FV HOB

If the FvImage buffer is not at its required alignment, then ASSERT().
Also update the function header description of BuildFv(2)Hob()
correspondingly.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=205

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>