rtc: remove 'setdate' test program

The tool is not embedded in the testing framework. 'rtc' from rtc-tools
serves as a much better programming example. No need to carry this tool
in the kernel tree.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20250320103433.11673-1-wsa+renesas@sang-engineering.com


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