ARM: dts: ti: align panel timings node name with dtschema

ARM: dts: ti: align panel timings node name with dtschema

DT schema expects panel timings node to follow certain pattern,
dtbs_check warnings:

  am335x-pdu001.dtb: display-timings: '240x320p16' does not match any of the regexes: '^timing', 'pinctrl-[0-9]+'

Linux drivers do not care about node name, so this should not have
effect on Linux.

Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> # For DaVinci
Link: https://lore.kernel.org/r/20240509104813.216655-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>