ext: simplelink: Add posix api and pthread support to Kconfig

When using the wifi driver, we should automatically select
CONFIG_POSIX_API and CONFIG_PTHREAD_IPC. This is necessary given the
code in the new SimpleLink host driver from the SimpleLink SDK uses
pthread and sem.

Signed-off-by: Vincent Wan <vincent.wan@linaro.org>
diff --git a/ext/hal/ti/simplelink/Kconfig b/ext/hal/ti/simplelink/Kconfig
index fd17364..adc48f3 100644
--- a/ext/hal/ti/simplelink/Kconfig
+++ b/ext/hal/ti/simplelink/Kconfig
@@ -6,12 +6,15 @@
 # Notes:
 # SimpleLink drivers require types (stdint.h) from NEWLIB_LIBC
 # Selecting ERRNO lets host driver use Zephyr's __errno
+# Selecting PTHREAD_IPC and POSIX_API are needed to build the host driver
 config SIMPLELINK_HOST_DRIVER
 	bool "Build the SimpleLink WiFi Host Driver"
 	depends on HAS_CC3220SDK
 	depends on MULTITHREADING
 	select NEWLIB_LIBC
 	select ERRNO
+        select POSIX_API
+        select PTHREAD_IPC
 	help
 	  Build the SimpleLink host driver