qed: Initialize debug string array

Coverity complains of an uninitialized variable.

CID 120847 (#1 of 1): Uninitialized scalar variable (UNINIT)
3. uninit_use_in_call: Using uninitialized value *sw_platform_str when calling qed_dump_str_param. [show details]
1344        offset += qed_dump_str_param(dump_buf + offset,
1345                                     dump, "sw-platform", sw_platform_str);

Fix this by removing dead code that references sw_platform_str.

Fixes: 6c95dd8f

 ("qed: Update debug related changes")

Cc: Ariel Elior <aelior@marvell.com>
Cc: GR-everest-linux-l2@marvell.com
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Shai Malin <smalin@marvell.com>
Cc: Omkar Kulkarni <okulkarni@marvell.com>
Cc: Prabhakar Kushwaha <pkushwaha@marvell.com>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org (open list)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>