configure.ac: Reverse feature check logic for Ja Rule
configure.ac: Reverse feature check logic for Ja Rule

Eventually, the plugin variable $enable_usbdmx might take the following
values, with the following semantic:

 - auto: was set to auto by the user and its dependencies are met
 - yes: was set to yes by user and its dependencies are met
 - no: was set to no by the user OR its dependencies are not met

If Ja Rule is set to yes, the only bad value for $enable_usbdmx to have
is no, so it's easier to check that it's not "no" than the opposite.

ld3300/ola,ld3300/ola,ld3300/ola,ld3300/ola,ld3300/ola,ld3300/ola,ld3300/ola