staging: rtl8723au: core: Remove unneeded #ifdefs

In rtw_mlme_ext.c, nested #ifdef blocks form the following
structure inside the file:

 #ifdef CONFIG_8723AU_AP_MODE           (line 1323)
 [...]
 #ifdef CONFIG_8723AU_AP_MODE           (line 1720)
 [...]
 #endif
 (2 more ifdef blocks with CONFIG_8723AU_AP_MODE follow)
 [...]
 #endif /* CONFIG_8723AU_AP_MODE */     (line 1763)

The inner #ifdefs are unnecessary as they depend on the
same condition as the outer #ifdef and can thus be removed.

Signed-off-by: Andreas Ruprecht <andreas.ruprecht@fau.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>