The EBX register should be preserved for the IA32 C calling convention.
The use of the CPUID instruction was modifying the EBX register, so
we push and pop EBX.
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@9573 6f19259b-4bc3-4df7-8a09-765794883524