mc146818rtc: Include mc146818rtc_regs.h directly in mc146818rtc.c

mc146818rtc: Include mc146818rtc_regs.h directly in mc146818rtc.c

Devices/boards wanting to use the MC146818 RTC don't need
the knowledge its internal registers. Move the "mc146818rtc_regs.h"
inclusion to mc146818rtc.c where it is required.

We can not move this file from include/hw/timer/ to hw/timer/ for
local inclusion because the ACPI FADT table use the RTC_CENTURY
register address.

Signed-off-by: Philippe Mathieu-Daudé <[email protected]>
Message-Id: <20191018133547[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Philippe Mathieu-Daudé <[email protected]>