[SCSI] megaraid: fix mega_internal_command oops

scsi_cmnd->cmnd was changed from a static array to a pointer post
2.6.25. It breaks mega_internal_command():

static int
mega_internal_command(adapter_t *adapter, megacmd_t *mc, mega_passthru *pthru)
{
...
	scb = &adapter->int_scb;
	memset(scb, 0, sizeof(scb_t));

	scmd = &adapter->int_scmd;
	memset(scmd, 0, sizeof(Scsi_Cmnd));

	sdev = kzalloc(sizeof(struct scsi_device), GFP_KERNEL);
	scmd->device = sdev;

	scmd->device->host = adapter->host;
	scmd->host_scribble = (void *)scb;
	scmd->cmnd[0] = MEGA_INTERNAL_CMD;

mega_internal_command() uses scsi_cmnd allocated internally so
scmd->cmnd is NULL here. This patch adds a static array for cdb to
adapter_t and uses it here. This also uses
scsi_allocate_command/scsi_free_command, the recommended way to
allocate struct scsi_cmnd since the driver might use sense_buffer in
struct scsi_cmnd.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reviewed-by: Boaz Harrosh <bharrosh@panasas.com>
Tested-by: Pascal Terjan <pterjan@gmail.com>
Reported-by: Pascal Terjan <pterjan@gmail.com>
Acked-by: "Yang, Bo" <Bo.Yang@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>