fix integer overflow warning in i2o_block

drivers/message/i2o/i2o_block.c: In function 'i2o_block_transfer':
drivers/message/i2o/i2o_block.c:837: warning: integer overflow in expression

msg->u.head[1] = cpu_to_le32(I2O_CMD_PRIVATE << 24 | HOST_TID << 12 | tid);
and I2O_CMD_PRIVATE is defined as 0xFF.  This gets "0xFF0100 | tid" and fits
into 32-bit unsigned but not into 32-bit signed integer properly.  Target
value is defined as u32 so the claculation does not fit during computation.

Change local variable tid to u32 so the whole expression is of u32 type and
fits well into u32 result.

Signed-off-by: Meelis Roos <mroos@linux.ee>
Cc: "Salyzyn, Mark" <mark_salyzyn@adaptec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>