m68k/apollo: Rename "timer" to "apollo_timer"

In file included from include/linux/kgdb.h:17,
                 from include/linux/fb.h:8,
                 from drivers/video/dnfb.c:15:
include/linux/serial_8250.h:71: error: expected identifier or ‘(’ before numeric constant
include/linux/serial_8250.h:72: error: expected ‘;’ before ‘struct’
make[1]: *** [drivers/video/dnfb.o] Error 1

This is caused by

    #define timer (IO_BASE + timer_physaddr)

in <asm/apollohw.h>, which conflicts with the new "timer" struct member in
<linux/serial_8250.h>.

Rename "timer" to "apollo_timer", as it's a way too generic name for a
global #define.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
--
http://kisskb.ellerman.id.au/kisskb/buildresult/6739606/