Vlv2TbltDevicePkg FvbRuntimeDxe: Fix CalculateCheckSum16 input incorrect length

Vlv2TbltDevicePkg FvbRuntimeDxe: Fix CalculateCheckSum16 input incorrect length

The input length should be "The size, in bytes, of Buffer.",
the divide sizeof (UINT16) operation is not needed and incorrect.

Cc: David Wei <david.wei@intel.com>
Cc: Tim He <tim.he@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: David Wei <david.wei@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18563 6f19259b-4bc3-4df7-8a09-765794883524