sparc32: remove stale RTC_PORT definition

sparc32:allmodconfig fails to build in next-20160602 as follows.

In file included from drivers/block/floppy.c:185:0:
include/linux/mc146818rtc.h: In function 'mc146818_is_updating':
include/linux/mc146818rtc.h:138:9: error: 'rtc_port' undeclared (first use in this function)
include/linux/mc146818rtc.h:138:9: note: each undeclared identifier is reported only once for each function it appears in
include/linux/mc146818rtc.h: In function 'mc146818_get_time':
include/linux/mc146818rtc.h:172:17: error: 'rtc_port' undeclared (first use in this function)
include/linux/mc146818rtc.h: In function 'mc146818_set_time':
include/linux/mc146818rtc.h:278:8: error: 'rtc_port' undeclared (first use in this function)
scripts/Makefile.build:295: recipe for target 'drivers/block/floppy.o' failed

The reason is a duplicate definition of the RTC_PORT macro. The
one in arch/sparc/include/asm/io_32.h was apparently used a long time
ago for the drivers/char/rtc.c driver that is not available on SPARC
any more, since we now select 'RTC_CLASS' unconditionally.

Removing the macro fixes the build problem, and for consistency,
this also removes the RTC_ALWAYS_BCD macro and the comment for both.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: fd09cc80165c ("rtc: cmos: move mc146818rtc code out of asm-generic/rtc.h")
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>