meta-ohos: Add meta-raspberrypi layer

bblayers.conf.sample: Path for the BBLAYERS has been added for
                      meta-raspberrypi.
conf-notes.txt:       Supported machines type has been updated.
local.conf.sample:    MACHINE type has been added for build argument.

Signed-off-by: Sudhesh Kumar <sudhesh.kumar.kuppusamy@huawei.com>
13 jobs for !101 with rasberrypi in 42 minutes and 45 seconds (queued for 18 seconds)
latest detached
Status Job ID Name Coverage
  Compliance
passed #15183
dco

00:00:11

 
  Build
passed #15195
large-disk
freertos-armv5

00:03:37

passed #15186
large-disk
linux-qemu-arm

00:10:46

passed #15187
large-disk
linux-qemu-arm64

00:12:58

passed #15184
large-disk
linux-qemu-x86

00:11:22

passed #15185
large-disk
linux-qemu-x86_64

00:11:39

passed #15189
large-disk
linux-seco-imx8mm-c61

00:11:38

passed #15188
large-disk
linux-seco-intel-b68

00:13:30

passed #15190
large-disk
linux-stm32mp1-av96

00:28:17

passed #15194
large-disk
zephyr-96b-avenger

00:02:40

passed #15193
large-disk
zephyr-96b-nitrogen

00:02:59

passed #15192
large-disk
zephyr-qemu-cortex-m3

00:03:21

passed #15191
large-disk
zephyr-qemu-x86

00:03:25