parport: gsc: remove DMA leftover code

This driver does not actually work with DMA mode, but still tries
to call ISA DMA interface functions that are stubbed out on
parisc, resulting in a W=1 build warning:

drivers/parport/parport_gsc.c: In function 'parport_remove_chip':
drivers/parport/parport_gsc.c:389:20: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
  389 |    free_dma(p->dma);

Remove the corresponding code as a prerequisite for turning on -Wempty-body
by default in all kernels.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Helge Deller <deller@gmx.de>