dt-bindings: rtc: mcp795: move to trivial-rtc

The current mcp795 bindings in text format do not support validation and
are missing the optional interrupt property that is currently supported.

Adding the missing property makes the bindings identical to the existing
trivial-rtc bindings.

Add maxim,mcp795 to the trivial-rtc bindings and delete current .txt
bindings

Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230906-topic-rtc_mcp795_yaml-v3-1-5262f1b39920@gmail.com


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