KVM: VMX: join functions that disable x2apic msr intercepts

vmx_disable_intercept_msr_read_x2apic() and
vmx_disable_intercept_msr_write_x2apic() differed only in the type.
Pass the type to a new function.

[Ordered and commented TPR intercept according to Paolo's suggestion.]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>