zephyr-demo-smarthome-led: change MAC to non-default

This demo a.k.a. blueprint is meant to be used with two Nitrogens
flashed with the same firmware, although modified by different recipes.
Since Nitrogens are expected to work simulataneously in the same
environment, connected to the same smart home central, they need to
have different MAC addresses. Add `sed` command to one of the recipes,
to change MAC.

Signed-off-by: Wojciech Zmuda <wojciech.zmuda@huawei.com>
13 jobs for !105 with fix/blueprint-led-mac in 28 minutes and 46 seconds (queued for 3 seconds)
latest detached
Status Job ID Name Coverage
  Compliance
passed #14699
dco

00:00:03

 
  Build
passed #14711
large-disk
freertos-armv5

00:01:15

passed #14702
large-disk
linux-qemu-arm

00:11:27

passed #14703
large-disk
linux-qemu-arm64

00:11:11

passed #14700
large-disk
linux-qemu-x86

00:10:48

passed #14701
large-disk
linux-qemu-x86_64

00:10:48

passed #14705
large-disk
linux-seco-imx8mm-c61

00:11:32

passed #14704
large-disk
linux-seco-intel-b68

00:12:20

passed #14706
large-disk
linux-stm32mp1-av96

00:28:42

passed #14710
large-disk
zephyr-96b-avenger

00:04:12

passed #14709
large-disk
zephyr-96b-nitrogen

00:04:23

passed #14708
large-disk
zephyr-qemu-cortex-m3

00:04:19

passed #14707
large-disk
zephyr-qemu-x86

00:04:03