ataflop: Killl warning about unused variable flags

After commit e0c09786 ("ataflop: remove
buggy/commented-out IRQ disable from do_fd_request()") the `flags' variable
became unused:

drivers/block/ataflop.c:1473: warning: unused variable 'flags'

Hence remove it.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>