rtc: m48t86: remove unused platform_data

rtc: m48t86: remove unused platform_data

All users of this driver have been updated to allow the driver to
manage it's own resources and do the read/write operations internally.
The m48t86_ops are no longer used.

Remove the platform_data header and the support code in the driver.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>