Staging: remove stlc45xx driver

It's no longer needed as the p54spi driver is the same thing,
under a different name and in the correct portion of the kernel tree.


Cc: Javier Martinez Canillas <martinez.javier@gmail.com>
Cc: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>