staging/rtl8192e: Fix compile warning 'is static but declared in .. which is not static'

When compiling this driver I get these compile warnings:

rtllib.h:2573:2: warning: '______f' is static but declared in inline
function 'rtllib_is_empty_essid' which is not static [enabled by
default]
rtllib.h:2579:3: warning: '______f' is static but declared in inline
function 'rtllib_is_empty_essid' which is not static [enabled by
default]
rtllib.h:2594:2: warning: '______f' is static but declared in inline
function 'rtllib_is_valid_mode' which is not static [enabled by default]
rtllib.h:2599:2: warning: '______f' is static but declared in inline
function 'rtllib_is_valid_mode' which is not static [enabled by default]
rtllib.h:2604:2: warning: '______f' is static but declared in inline
function 'rtllib_is_valid_mode' which is not static [enabled by default]
rtllib.h:2618:3: warning: '______f' is static but declared in inline
function 'rtllib_get_hdrlen' which is not static [enabled by default]
rtllib.h:2620:3: warning: '______f' is static but declared in inline
function 'rtllib_get_hdrlen' which is not static [enabled by default]

These functions are declared as extern inline but not 'overloaded'
anywhere so we can declare them static inline and get rid of the
warnings.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>