samples: drivers: video: tcpserversink: fix board definition

By having an "auto-fallback" mechanism, the VIDEO_SW_GENERATOR did shadow
the fact that "platform:mimxrt1064_evk:SHIELD=dvp_fpc24_mt9m114" was
missing the full specification, and therefore was not matched at all:
the shield was not selected, but the CI still worked.

Signed-off-by: Josuah Demangeon <me@josuah.net>

Author: josuah

samples/drivers/video/tcpserversink/sample.yaml

@@ -13,6 +13,6 @@ tests:
       - video
       - netif
     integration_platforms:
-      - mimxrt1064_evk
+      - mimxrt1064_evk/mimxrt1064
     extra_args:
-      - platform:mimxrt1064_evk:SHIELD=dvp_fpc24_mt9m114
+      - platform:mimxrt1064_evk/mimxrt1064:SHIELD=dvp_fpc24_mt9m114