wifi: remove configure checks for suitable linux/nl80211.h header

The check doesn't seem useful, because it does not result in a fallback
or a different build.

Just assume <linux/nl80211.h> is valid. In case it is not, we will get a
build failure later. That is just as good.

configure.ac

@@ -224,24 +224,6 @@ else
 fi
 AM_CONDITIONAL(WITH_WEXT, test x"${ac_with_wext}" = x"yes")
 
-AC_MSG_CHECKING([Linux kernel nl80211 headers])
-AC_COMPILE_IFELSE(
-                  [AC_LANG_PROGRAM(
-                                   [[#ifndef __user
-                                     #define __user
-                                     #endif
-                                     #include <sys/types.h>
-                                     #include <linux/types.h>
-                                     #include <sys/socket.h>
-                                     #include <linux/nl80211.h>]],
-                                   [[int a = NL80211_RATE_INFO_BITRATE; a++;]])],
-                  [ac_have_nl80211=yes],
-                  [ac_have_nl80211=no])
-AC_MSG_RESULT($ac_have_nl80211)
-if test "$ac_have_nl80211" = no; then
-	AC_MSG_ERROR(Linux kernel development header linux/nl80211.h not installed or not functional)
-fi
-
 dnl
 dnl Default to using wpa_supplicant but allow IWD as wifi backend
 dnl

meson.build

@@ -269,23 +269,6 @@ if dist_version != ''
 endif
 
 enable_wifi = get_option('wifi')
-if enable_wifi
-  nl80211_src = '''
-    #ifndef __user
-    #define __user
-    #endif
-    #include <sys/types.h>
-    #include <linux/types.h>
-    #include <sys/socket.h>
-    #include <linux/nl80211.h>
-    int main() {
-      int a = NL80211_RATE_INFO_BITRATE;
-      a++;
-    }
-  '''
-
-  assert(cc.compiles(nl80211_src), 'Linux kernel development header linux/nl80211.h not installed or not functional')
-endif
 config_h.set10('WITH_WIFI', enable_wifi)
 
 enable_iwd = get_option('iwd')