xen/pvh: remove duplicated include from enlighten.c

Remove duplicated include.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

arch/x86/xen/enlighten.c

@@ -46,7 +46,6 @@
 #include <xen/hvm.h>
 #include <xen/hvc-console.h>
 #include <xen/acpi.h>
-#include <xen/features.h>
 
 #include <asm/paravirt.h>
 #include <asm/apic.h>