x86/xsaves: ebx may return wrong value using CPUID eax=0xd,ecx =1

x86/xsaves: ebx may return wrong value using CPUID eax=0xd,ecx =1

Refer to SDM Volume 1 Extended Region of an XSAVE Area. The value returned
by ecx[1] with cpuid function 0xd and sub-function i (i>1) indicates
the alignment of the state component i when the compacted format of the
extended region of an xsave area is used.

So when hvm guest using CPUID eax=0xd, ecx=1 to get the size of area
used for compacted format, we need to take alignment into consideration.

tools side is fixed by
"tools/libxc: Calculate xstate cpuid leaf from guest information"
by Andrew Cooper

Signed-off-by: Shuai Ruan <shuai.ruan@intel.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>