OvmfPkg: LoadLinuxLib: Zero kernel parameters instead of passing garbage

OvmfPkg: LoadLinuxLib: Zero kernel parameters instead of passing garbage

We're supposed to zero everything in the kernel bootparams that we don't
explicitly initialise, other than the setup_header from 0x1f1 onwards
for a precisely defined length, which is copied from the bzImage.

We're *not* supposed to just pass the garbage that we happened to find
in the bzImage file surrounding the setup_header.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14052 6f19259b-4bc3-4df7-8a09-765794883524