bnxt_en: Enhance stats context reservation logic

bnxt_en: Enhance stats context reservation logic

When the firmware advertises that the device is capable of supporting
port mirroring on RoCE device, reserve one additional stat_ctx.
To support port mirroring feature, RDMA driver allocates one stat_ctx
for exclusive use in RawEth QP.

Signed-off-by: Saravanan Vajravel <saravanan.vajravel@broadcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Kashyap Desai <kashyap.desai@broadcom.com>
Reviewed-by: Selvin Xavier <selvin.xavier@broadcom.com>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Link: https://patch.msgid.link/20250822040801.776196-2-kalesh-anakkur.purayil@broadcom.com
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Leon Romanovsky <leon@kernel.org>