hamradio: fix macro redefine warning

commit 16517829f2e02f096fb5ea9083d160381127faf3 upstream.

MIPS/IA64 define END as assembly function ending, which conflict
with END definition in mkiss.c, just undef it at first

Reported-by:  <lkp@intel.com>
Signed-off-by: Huang Pei <huangpei@loongson.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>