debug/gdb: hide Linaro options by default

It can be quite confusing for a new-comer to find strange
version numbers for gdb, so hide the Linaro versions by
default.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# Alpha specific configuration file

config ARCH_alpha

    select ARCH_SUPPORTS_32

    select ARCH_DEFAULT_32

    select ARCH_USE_MMU

    select ARCH_SUPPORT_CPU

    select ARCH_SUPPORT_TUNE

    help

      The Alpha architecture.