external-arm-sdk-toolchain: Fix parsing error with INCOMPATIBLE_LICENSE

This change fixes parsing error that occurs when INCOMPATIBLE_LICENSE =
"GPLv3" by defining EAT_BFD_LICENSE, EAT_GDB_LICENSE and EAT_RLE_LICENSE
in license.inc and requiring it in external-arm-sdk-toolchain.bb

Definitions in external-arm-toolchain-versions.inc are made redundant so
they are removed.

Signed-off-by: Timothy Mertz <timothy.mertz@garmin.com>
Signed-off-by: Joshua Watt <Joshua.Watt@garmin.com>
Reviewed-by: Denys Dmytriyenko <denis@denix.org>
Signed-off-by: Jon Mason <jon.mason@arm.com>