Update CHANGELOG for 4.3.0 and collect Tested-by tags.

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Tested-by: Joakim Bech <joakim.bech@linaro.org> (RPi 3B v1.2)
Tested-by: Jerome Forissier <jerome.forissier@linaro.org> (vexpress-qemu_armv8a)
Tested-by: Jerome Forissier <jerome.forissier@linaro.org> (vexpress-qemu_virt)
Tested-by: Igor Opaniuk <igor.opaniuk@gmail.com> (Poplar)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx6dlsabresd)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx6qsabresd)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx6sllevk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx6ulevk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx6ulzevk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx7dsabresd)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx7ulpevk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx8dxlevk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx8mmevk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx8mnevk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx8mqevk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx8mpevk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx8qmmek)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx8qxpmek)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx8ulpevk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (imx-mx93evk)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (LS1046A-RDB)
Tested-by: Sahil Malhotra <sahil.malhotra@nxp.com> (LX2160A-RDB)
Tested-by: Jens Wiklander <jens.wiklander@linaro.org> (rockchip-rk3399, Rockpi4B)
Tested-by: Jens Wiklander <jens.wiklander@linaro.org> (Hikey)
Tested-by: Jens Wiklander <jens.wiklander@linaro.org> (imx-mx8mqevk)
Tested-by: Jens Wiklander <jens.wiklander@linaro.org> (FVP)
Tested-by: Imre Kis <imre.kis@arm.com> (fvp-ts)
Tested-by: Etienne Carriere <etienne.carriere@foss.st.com> (stm32mp1-157C_EV1)
Tested-by: Etienne Carriere <etienne.carriere@foss.st.com> (stm32mp1-157C_EV1_SCMI)
Tested-by: Etienne Carriere <etienne.carriere@foss.st.com> (stm32mp1-157C_DK2_SCMI)
Tested-by: Gatien Chevallier <gatien.chevallier@foss.st.com> (stm32mp1-157C_DK2)
Tested-by: Gatien Chevallier <gatien.chevallier@foss.st.com> (stm32mp1-135F_DK)