bnxt_en: Fix backing store V2 logic

bnxt_en: Fix backing store V2 logic

The current code determines the last backing store valid type during
bnxt_hwrm_func_backing_store_qcaps_v2().  In effect, the last type
is determined based on what firmware advertises.  The more correct
way is to determine it based on what the driver is configuring.  The
driver may not configure all the backing store types advertised by
firmware.

Move the logic to determine the last type to bnxt_backing_store_cfg_v2().
We need to pass the legacy enable flags to the function in case only
the legacy types are being configured.

Fixes: 236e237f8ffe ("bnxt_en: Add support for HWRM_FUNC_BACKING_STORE_CFG_V2 firmware calls")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Link: https://lore.kernel.org/r/20231201223924.26955-2-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>