m68k: mvme147, mvme16x: Adopt rtc-m48t59 platform driver

Both mvme147 and mvme16x platforms have their own RTC driver
implementations that duplicate functionality provided by the rtc-m48t59
driver. Adopt the rtc-m48t59 driver and remove the other ones.

Tested-by: Daniel Palmer <daniel@0x0f.com>
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/19a16bcc94c42ea9c5397b37b1918c2937e3faab.1731450735.git.fthain@linux-m68k.org


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>