gigaset: silence GCC warning for unused 'format_ie'

gigaset: silence GCC warning for unused 'format_ie'

commit 6ba6047bf99cf4ade4f63b6b3d97cc3ad763b678 upstream.

Building Gigaset's CAPI support without Gigaset's debugging enabled
triggers this GCC warning:
    'format_ie' defined but not used [-Wunused-function]

Silence this warning by wrapping format_ie() in an "#ifdef
CONFIG_GIGASET_DEBUG" and "#endif" pair.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>