net: ieee802154/adf7242: syntax error ifdef DEBUG

If DEBUG is defined, a superfluous closing brace
is introduced.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: David S. Miller <davem@davemloft.net>