rtl8192e: Don't copy huge struct by value (and make it const).

rtllib_is_shortslot() takes one argument - a struct that's more than a
kilobyte large. It should take a pointer instead of copying such a
huge struct - and the argument might as well be declared 'const' now
that we are at it, since it is not modified. This patch makes these
changes.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>