V4L2: Allow device to be specified with option.
V4L2: Allow device to be specified with option.

Currently the V4L2 device to be used can only be set via the media URL.
This patch allows the :v4l2-dev option to set the device as well.
Setting the device via the media URL still takes precedence.

This is useful if a program auto-detects the V4L2 device so that the
media URL only needs to contain e.g. the tuner settings.

Signed-off-by: Rémi Denis-Courmont <f0699137713be92736351a0674e79536595e4a60@remlab.net>

krichter722/vlc,jomanmuk/vlc-2.1,shyamalschandra/vlc,krichter722/vlc,krichter722/vlc,jomanmuk/vlc-2.1,xkfz007/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,vlc-mirror/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,vlc-mirror/vlc,vlc-mirror/vlc,shyamalschandra/vlc,shyamalschandra/vlc,shyamalschandra/vlc,krichter722/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,shyamalschandra/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,krichter722/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc,krichter722/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,krichter722/vlc,vlc-mirror/vlc,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,xkfz007/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,xkfz007/vlc,xkfz007/vlc,vlc-mirror/vlc,xkfz007/vlc,vlc-mirror/vlc-2.1,xkfz007/vlc,vlc-mirror/vlc