KVM: nVMX: Add macros to simplify nested MSR interception setting

KVM: nVMX: Add macros to simplify nested MSR interception setting

Add macros nested_vmx_merge_msr_bitmaps_xxx() to simplify nested MSR
interception setting. No function change intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
Tested-by: Xudong Hao <xudong.hao@intel.com>
Tested-by: Manali Shukla <manali.shukla@amd.com>
Link: https://patch.msgid.link/20251206001720.468579-31-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>