ARM Juno GCC5 support note.
ARM Juno GCC5 support note.

It fixes #822 (ramdisk.img size)

Reviewed-by: Joakim Bech <741f90e2a7f4d9afbad8bd50be20560f4cf38962@linaro.org>
Tested-by: Miraje Gentilal <88da39114cc20ac2ee28021510331c18193108e9@hotmail.com> (Juno-r2)
Signed-off-by: Miraje Gentilal <88da39114cc20ac2ee28021510331c18193108e9@hotmail.com>

matt2048/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,matt2048/optee_os,matt2048/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,matt2048/optee_os