prestera: fix fallback to previous version on same major version

When both supported and previous version have the same major version,
and the firmwares are missing, the driver ends in a loop requesting the
same (previous) version over and over again:

    [   76.327413] Prestera DX 0000:01:00.0: missing latest mrvl/prestera/mvsw_prestera_fw-v4.1.img firmware, fall-back to previous 4.0 version
    [   76.339802] Prestera DX 0000:01:00.0: missing latest mrvl/prestera/mvsw_prestera_fw-v4.0.img firmware, fall-back to previous 4.0 version
    [   76.352162] Prestera DX 0000:01:00.0: missing latest mrvl/prestera/mvsw_prestera_fw-v4.0.img firmware, fall-back to previous 4.0 version
    [   76.364502] Prestera DX 0000:01:00.0: missing latest mrvl/prestera/mvsw_prestera_fw-v4.0.img firmware, fall-back to previous 4.0 version
    [   76.376848] Prestera DX 0000:01:00.0: missing latest mrvl/prestera/mvsw_prestera_fw-v4.0.img firmware, fall-back to previous 4.0 version
    [   76.389183] Prestera DX 0000:01:00.0: missing latest mrvl/prestera/mvsw_prestera_fw-v4.0.img firmware, fall-back to previous 4.0 version
    [   76.401522] Prestera DX 0000:01:00.0: missing latest mrvl/prestera/mvsw_prestera_fw-v4.0.img firmware, fall-back to previous 4.0 version
    [   76.413860] Prestera DX 0000:01:00.0: missing latest mrvl/prestera/mvsw_prestera_fw-v4.0.img firmware, fall-back to previous 4.0 version
    [   76.426199] Prestera DX 0000:01:00.0: missing latest mrvl/prestera/mvsw_prestera_fw-v4.0.img firmware, fall-back to previous 4.0 version
    ...

Fix this by inverting the check to that we aren't yet at the previous
version, and also check the minor version.

This also catches the case where both versions are the same, as it was
after commit bb5dbf2c ("net: marvell: prestera: add firmware v4.0
support").

With this fix applied:

    [   88.499622] Prestera DX 0000:01:00.0: missing latest mrvl/prestera/mvsw_prestera_fw-v4.1.img firmware, fall-back to previous 4.0 version
    [   88.511995] Prestera DX 0000:01:00.0: failed to request previous firmware: mrvl/prestera/mvsw_prestera_fw-v4.0.img
    [   88.522403] Prestera DX: probe of 0000:01:00.0 failed with error -2

Fixes: 47f26018

 ("net: marvell: prestera: try to load previous fw version")
Signed-off-by: Jonas Gorski <jonas.gorski@bisdn.de>
Acked-by: Elad Nachman <enachman@marvell.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: Taras Chornyi <taras.chornyi@plvision.eu>
Link: https://lore.kernel.org/r/20230802092357.163944-1-jonas.gorski@bisdn.de


Signed-off-by: Jakub Kicinski <kuba@kernel.org>