m68k: sun3: Remove unused orig_baddr in free_baddr()

When building with W=1:

    arch/m68k/sun3/sun3dvma.c: In function ‘free_baddr’:
    arch/m68k/sun3/sun3dvma.c:208:23: warning: variable ‘orig_baddr’ set but not used [-Wunused-but-set-variable]
      196 |         unsigned long orig_baddr;
	  |                       ^~~~~~~~~~

Fix this by removing the unused variable and assignment, which were
futile since their introduction in v2.4.5.2.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/c705b6186241dfe9a5bdcb71720b8697fa5c801f.1694613528.git.geert@linux-m68k.org