[TG3]: Constify firmware structs

Constify largish areas of firmware data in Tigon3 ethernet driver.

non-const:

lsmod:
tg3                   101404  0

objdump -x:
.rodata 000003e8
.data 00004a0c

ls -l:
-rw-r--r-- 1 root root 114404 2006-08-19 21:36 drivers/net/tg3.ko

const:

lsmod:
tg3                   101404  0

objdump -x:
.rodata 000042c8
.data 00000b4c

ls -l:
-rw-r--r-- 1 root root 114532 2006-08-19 21:06 drivers/net/tg3.ko

Signed-off-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>