wifi/hostap: remove select POSIX_API

These libraries only need the `zephyr/posix` system headers on path, not
the various implied options in the `POSIX_API` symbol.

Signed-off-by: Jordan Yates <jordan@embeint.com>

Author: JordanYates

drivers/wifi/nxp/Kconfig.nxp

@@ -999,7 +999,7 @@ if NXP_WIFI_SMOKE_TESTS
 
 config NXP_WIFI_SIGMA_AGENT
 	bool "Wi-Fi Alliance Sigma Agent Support"
-	select POSIX_API
+	select POSIX_SYSTEM_HEADERS
 	select POSIX_THREADS
 	select PTHREAD_CREATE_BARRIER
 	select POSIX_TIMERS

modules/hostap/Kconfig

@@ -7,7 +7,7 @@
 
 config WIFI_NM_WPA_SUPPLICANT
 	bool "WPA Suplicant from hostap project [EXPERIMENTAL]"
-	select POSIX_API
+	select POSIX_SYSTEM_HEADERS
 	select POSIX_NETWORKING
 	select POSIX_TIMERS
 	select POSIX_SIGNALS