linux-raspberrypi-dev: drop protocol=git and add LINUX_RPI_KMETA_BRANCH
linux-raspberrypi-dev: drop protocol=git and add LINUX_RPI_KMETA_BRANCH

* update SRC_URI format to use the same as linux-raspberrypi_5.10.bb
  and linux-raspberrypi_5.4.bb by dropping protocol=git and using
  LINUX_RPI_KMETA_BRANCH

* protocol=git was dropped from other linux-raspberrypi recipes in:

  commit 0381ac4d08abdb3dda815e6594536ac774baad8d
  Author: Timm Eversmeyer <saeugetier@googlemail.com>
  Date:   Wed Sep 11 07:08:50 2019 +0200

    raspberrypi-linux: removed protocoll setting from SRC_URI

    Default protocoll for git will be used. Default setting is in the most case https.

    Signed-off-by: Timm Eversmeyer saeugetier@gmail.com

Signed-off-by: Martin Jansa <516df3ff67e1fa5d153800b15fb204c0a1a389dc@gmail.com>

agherzan/meta-raspberrypi,agherzan/meta-raspberrypi,schnitzeltony/meta-raspberrypi,schnitzeltony/meta-raspberrypi,agherzan/meta-raspberrypi,agherzan/meta-raspberrypi,agherzan/meta-raspberrypi,schnitzeltony/meta-raspberrypi,agherzan/meta-raspberrypi