arm: socfpga: gen5: sync devicetrees to Linux

This is again a sync to linux-next + pending patches in Dinh's tree at
commit 1c909b2dfe6a ("ARM: dts: socfpga: update more missing reset
properties")'

It adds missing peripheral reset properties to socfpga.dtsi and removes
U-Boot specific leftovers from socfpga_cyclone5_socrates.dts.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>