[WIFI][VTS] Don't call RequestDriverDebugDump API if not supported

The RequestDriverDebugDump API has a capability bit indicating if
supported on device. Calling if not supported should additionally
return ERROR_NOT_SUPPORTED - but does not today. This is arguably
not a valid issue - should not call API if already known not to be
supported.

Remove test for this (questionable) condition until decide on proper
semantics.

Bug: 36562856
Test: test passes
Change-Id: Ic8a1c8b5f77a1b1767c0efc9735731084dfde7cc