rtc: rtc-m48t86: move m48t86.h to platform_data

The header for the rtc-m48t86 platform-data should be in
include/linux/platform_data.

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
rtc: rtc-m48t86: add hooks to support driver side memory mapping

If platform_data is not defined (as before), then named memory io
ranges need to be defined ("rtc_index" and "rtc_data").  The driver
then maps those regions and uses them as the RTC index and data
addresses.

Does compile with the following warnings, I cannot see the codepath
affected myself:
----
drivers/rtc/rtc-m48t86.c: In function ‘m48t86_rtc_probe’:
drivers/rtc/rtc-m48t86.c:180: warning: ‘res_index’ may be used uninitialized in this function
drivers/rtc/rtc-m48t86.c:180: warning: ‘res_data’ may be used uninitialized in this function
----

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
rtc: rtc-m48t86: add detect method for RTC

The m48t86 has 114 bytes of user space available, so we can use this
space to detect for the presence of the RTC.

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
arm: orion5x: move ts78xx to use rtc-m48t86 driver side memory interface

Remove platform_data hooks into rtc-m48t86 and use named resource regions.

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
arm: ep93xx: move ts72xx to use rtc-m48t86 driver side memory interface

Remove platform_data hooks into rtc-m48t86 and use named resource regions.

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
rtc: rtc-m48t86: add devicetree bindings

Add devicetree bindings (and documentation) for rtc-m48t86.

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>