dshowsrcwrapper: fix regression on device selection

Do not take device_name if a device has been specified. Do not take device_index into account if a device or a device name has been specified.
25 jobs for master in 89 minutes and 4 seconds (queued for 51 seconds)
latest
Status Job ID Name Coverage
  Preparation
passed #528083
gst indent

00:00:41

passed #528082
manifest

00:00:28

 
  Build
passed #528309
build cerbero android universal

00:12:42

passed #528311
build cerbero cross win32

00:11:24

passed #528310
build cerbero cross win64

00:06:12

passed #528091
build cerbero fedora x86_64

00:42:53

manual #528096
gst-ios-12.2 allowed to fail manual
build cerbero ios universal
passed #528307
gst-macos-10.14
build cerbero macos x86_64

00:08:18

passed #528084
build fedora x86_64

00:10:05

passed #528090
docker windows 1607
build msys2

00:11:46

passed #528085
build nodebug fedora x86_64

00:09:52

passed #528086
build static fedora x86_64

00:14:22

passed #528087
build static nodebug fedora x86_64

00:13:33

passed #528088
docker windows 1607
build vs2017 amd64

00:09:53

passed #528089
docker windows 1607
build vs2017 x86

00:09:52

failed #528092
build cerbero android universal

01:00:01

failed #528093
build cerbero cross win32

01:00:00

failed #528094
build cerbero cross win64

01:00:01

failed #528095
gst-macos-10.14
build cerbero macos x86_64

01:00:00

 
  Test
passed #528097
check fedora

00:04:15

passed #528399
integration testsuites fedora

00:14:20

passed #528099
valgrind bad

00:08:09

canceled #528098
integration testsuites fedora

00:12:22

 
  Integrate
passed #528100
android universal examples

00:06:02

passed #528101
documentation

00:06:28