drivers/net/lan91c96.c: Fix GCC 4.6 warning

Fix:
lan91c96.c: In function 'dump_memory_info':
lan91c96.c:157:7: warning: variable 'mem_info' set but not used
[-Wunused-but-set-variable]
lan91c96.c: In function 'smc_send_packet':
lan91c96.c:320:16: warning: variable 'ioaddr' set but not used
[-Wunused-but-set-variable]

Signed-off-by: Anatolij Gustschin <agust@denx.de>