Remove freertos-plus-tcp submodule.

This was added accidentally and is not used.

.gitmodules

diff --git a/.gitmodules b/.gitmodules
index 88cbeef..2bc1dc4 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,6 +4,3 @@
 [submodule "sdk/third_party/microvium"]
 	path = sdk/third_party/microvium
 	url = https://github.com/coder-mike/microvium
-[submodule "sdk/third_party/freertos-plus-tcp"]
-	path = sdk/third_party/freertos-plus-tcp
-	url = https://github.com/FreeRTOS/FreeRTOS-Plus-TCP.git

sdk/third_party/freertos-plus-tcp

diff --git a/sdk/third_party/freertos-plus-tcp b/sdk/third_party/freertos-plus-tcp
deleted file mode 160000
index d70a21c..0000000
--- a/sdk/third_party/freertos-plus-tcp
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit d70a21ce03569118e030b348844477b92f5fd227