cpu flags: aliases: pclmuldq|pclmulqdq and ffxsr|fxsr_opt

cpu flags: aliases: pclmuldq|pclmulqdq and ffxsr|fxsr_opt

pclmulqdq: /proc/cpuinfo on Linux and all documentation I have seen uses
pclmulqdq as the flag name. As the only document using pclmuldq seems to
be the Intel CPUID documentation (Application Note 485), it looks like a
typo and not the correct name for the flag.

ffxsr: AMD docs refer to fxsr_opt as ffxsr, so allow this named to be
used too.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>