Replace use of VMX_ERROR with virReportError

Update the VMX shared code to use virReportError instead of
the VMX_ERROR custom macro
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

cfg.mk

@@ -507,7 +507,6 @@ sc_avoid_attribute_unused_in_header:
 
 msg_gen_function =
 msg_gen_function += VIR_ERROR
-msg_gen_function += VMX_ERROR
 msg_gen_function += lxcError
 msg_gen_function += regerror
 msg_gen_function += statsError