boards: arm: Add entropy dts chosen node for lpcxpresso55s69_cpu1

Adds an entropy dts chosen node for the lpcxpresso55s69_cpu1 board
configuration. Commit 50830385 added
this for the _cpu0 and _ns board configurations, but missed the _cpu1
board configuration.

Fixes sanitycheck build errors for network socket samples.

Signed-off-by: Maureen Helm <maureen.helm@nxp.com>