staging: comedi: amcc_s5933_58.h: remove unused file

Nothing in the comedi subsystem references this header file. It's
actually almost a straight copy of the addi_amcc_s5933.h file anyway.
Just remove the file.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>