ramips: remove useless resets properties from SoC dtsi

ramips: remove useless resets properties from SoC dtsi

These drivers don't request reset control. And most reset properties
even have incorrect reset source definitions.

1. interrupt controller, ref: arch/mips/ralink/irq.c
2. memory controller, ref: arch/mips/ralink/of.c
3. gpio controller, ref: drivers/gpio/gpio-ralink.c (local patch)
4. systic, ref: arch/mips/ralink/cevt-rt3352.c
5. pwm, ref: drivers/pwm/pwm-mediatek-ramips.c (local patch)

Tested on MT7620 && MT7628.

Signed-off-by: Shiji Yang <yangshiji66@qq.com>