KVM: x86: Rename gb_page_enable() to get_lpage_level() in kvm_x86_ops

Then the callback can provide the maximum supported large page level, which
is more flexible.

Also move the gb page support into x86_64 specific.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f4486f4..0fd0892 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4036,9 +4036,9 @@
 
 #undef _ER
 
-static bool vmx_gb_page_enable(void)
+static int vmx_get_lpage_level(void)
 {
-	return false;
+	return PT_DIRECTORY_LEVEL;
 }
 
 static inline u32 bit(int bitno)
@@ -4131,7 +4131,7 @@
 	.get_mt_mask = vmx_get_mt_mask,
 
 	.exit_reasons_str = vmx_exit_reasons_str,
-	.gb_page_enable = vmx_gb_page_enable,
+	.get_lpage_level = vmx_get_lpage_level,
 
 	.cpuid_update = vmx_cpuid_update,