rtc: spacemit: MFD_SPACEMIT_P1 as dependencies

rtc: spacemit: MFD_SPACEMIT_P1 as dependencies

RTC_DRV_SPACEMIT_P1 is a subdevice of P1 and should depend on
MFD_SPACEMIT_P1 rather than selecting it directly. Using 'select'
does not always respect the parent's dependencies, so 'depends on'
is the safer and more correct choice.

Additionally, the default value depends on MFD_SPACEMIT_P1 rather
than ARCH_SPACEMIT.

Signed-off-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
Acked-by: Alex Elder <elder@riscstar.com>
Link: https://patch.msgid.link/20251118-p1-kconfig-fix-v3-2-8839c5ac5db3@linux.spacemit.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>