toolchain: blackfin: Remove Blackfin toolchain 2011R1 release.

ADI officially supports the buildroot and related GNU toolchain for
Blackfin since ADI's 2012R1 release only. In order to avoid confusion,
it is better to remove the 2011R1 GNU toolchain for Blackfin. In
addition, the 2011R1 GNU toolchain for Blackfin doesn't support the
BF60x processors.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>