KVM: x86/mmu: Rename reset_rsvds_bits_mask()

Rename reset_rsvds_bits_mask() to reset_guest_rsvds_bits_mask() to make
it clearer that it resets the reserved bits check for guest's page table
entries.

Signed-off-by: Kai Huang <kai.huang@intel.com>
Message-Id: <efdc174b85d55598880064b8bf09245d3791031d.1650363789.git.kai.huang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>