staging: rtl8192su: move to EEPROM_93CX

this is basically a port of Larry Fingers Patch for rtl8187se to rtl8192su.
also removed some dead code.
plus cosmetics.

Signed-off-by: Florian Schilhabel <florian.c.schilhabel@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>