toolchain-external: bump version of Linaro ARMeb toolchain

The gdb version is 7.11.1 not 7.10 as stated in the link below [1].
See the manifest to check the version really used [2].

[1] https://releases.linaro.org/components/toolchain/binaries/5.3-2016.05
[2] https://releases.linaro.org/components/toolchain/binaries/5.3-2016.05/armeb-linux-gnueabihf/gcc-linaro-5.3.1-2016.05-linux-manifest.txt



Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>