USB: ssu100: remove duplicate #defines in ssu100

The ssu100 uses a TI16C550C UART so the SERIAL_ defines in this code
are duplicates of those found in serial_reg.h.  Remove the defines in
ssu100.c and use the ones in the header file.

Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>