arm64: dts: imx8ulp: add reserved memory for EdgeLock Enclave

Reserve 1MB of DDR for the EdgeLock Enclave. The enclave hardware can only
access DDR in the 0x80000000 - 0xafffffff window, so constrain the pool to
that range with alloc-ranges and let the kernel choose the placement rather
than hardcoding an address.

Provide this as a shared imx8ulp-firmware.dtsi that also enables the hsm0
node and wires up its memory-region, so every i.MX8ULP board can bring up
the enclave with a single include instead of duplicating the reserved
memory node. Include it from imx8ulp-evk.

Signed-off-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>