Add license identifier to files which Arm owns the copyright to,
and contain either BSD-3 or Apache-2.0 licenses. This is to address
license errors raised by scancode analysis.
Passed GreenTea CI.
Added RZ_A2XX and GR_MANGO to targets.json.
Added RZ_A2XX to mbedlib.json in lwipstack and netsocket/ppp.
Added TARGET_RZ_A2XX directory to targets/TARGET_RENESAS.
Added TARGET_RENESAS_EMAC directory to features/netsocket/emac-drivers.
Moved TARGET_RZ_A1_EMAC directory into the TARGET_RENESAS_EMAC directory below and renamed to TARGET_RZ_A1XX.
Added TARGET_RZ_A2XX directory to features/netsocket/emac-drivers/TARGET_RENESAS_EMAC.