mac80211_hwsim: allow setting iftype support

The mac80211_hwsim driver hard codes its supported interface types. For
testing purposes it would be valuable to allow changing these supported
types in order to simulate actual drivers than support a limited set of
iftypes. A new attribute was added to allow this:

- HWSIM_ATTR_IFTYPE_SUPPORT
	A u32 bit field of supported NL80211_IFTYPE_* bits

This will only enable/disable iftypes that mac80211_hwsim already
supports.

In order to accomplish this, the ieee80211_iface_limit structure needed
to be built dynamically to only include limit rules for iftypes that
the user requested to enable.

Signed-off-by: James Prestwood <james.prestwood@linux.intel.com>
[fix some indentation, add netlink error string]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/mac80211_hwsim.h

@@ -132,6 +132,7 @@ enum {
  * @HWSIM_ATTR_TX_INFO_FLAGS: additional flags for corresponding
  *	rates of %HWSIM_ATTR_TX_INFO
  * @HWSIM_ATTR_PERM_ADDR: permanent mac address of new radio
+ * @HWSIM_ATTR_IFTYPE_SUPPORT: u32 attribute of supported interface types bits
  * @__HWSIM_ATTR_MAX: enum limit
  */
 
@@ -160,6 +161,7 @@ enum {
 	HWSIM_ATTR_PAD,
 	HWSIM_ATTR_TX_INFO_FLAGS,
 	HWSIM_ATTR_PERM_ADDR,
+	HWSIM_ATTR_IFTYPE_SUPPORT,
 	__HWSIM_ATTR_MAX,
 };
 #define HWSIM_ATTR_MAX (__HWSIM_ATTR_MAX - 1)