Add more bits for the XSAVE features from CPUID 0xd, sub-function 1

%eax report.

Print the XSAVE features 0xd/1 in the boot banner.  The printcpuinfo()
is executed late enough so that XSAVE is already enabled.

There is no known to me off the shelf hardware that implements any
feature bits except XSAVEOPT, the list is taken from SDM rev. 50.  The
banner printing will allow us to note the hardware arrival.

Sponsored by:	    The FreeBSD Foundation
MFC after:	    1 week

sys/x86/include/specialreg.h

@@ -296,6 +296,9 @@
  * CPUID instruction 0xd Processor Extended State Enumeration Sub-leaf 1
  */
 #define	CPUID_EXTSTATE_XSAVEOPT	0x00000001
+#define	CPUID_EXTSTATE_XSAVEC	0x00000002
+#define	CPUID_EXTSTATE_XINUSE	0x00000004
+#define	CPUID_EXTSTATE_XSAVES	0x00000008
 
 /*
  * AMD extended function 8000_0007h edx info

sys/x86/x86/identcpu.c

@@ -932,6 +932,19 @@ printcpuinfo(void)
 				       );
 			}
 
+			if ((cpu_feature2 & CPUID2_XSAVE) != 0) {
+				cpuid_count(0xd, 0x1, regs);
+				if (regs[0] != 0) {
+					printf("\n  XSAVE Features=0x%b",
+					    regs[0],
+					    "\020"
+					    "\001XSAVEOPT"
+					    "\002XSAVEC"
+					    "\003XINUSE"
+					    "\004XSAVES");
+				}
+			}
+
 			if (via_feature_rng != 0 || via_feature_xcrypt != 0)
 				print_via_padlock_info();