platform/mellanox: mlxbf-tmfifo: Drop the Rx packet if no more descriptors

This commit fixes tmfifo console stuck issue when the virtual
networking interface is in down state. In such case, the network
Rx descriptors runs out and causes the Rx network packet staying
in the head of the tmfifo thus blocking the console packets. The
fix is to drop the Rx network packet when no more Rx descriptors.
Function name mlxbf_tmfifo_release_pending_pkt() is also renamed
to mlxbf_tmfifo_release_pkt() to be more approperiate.

Fixes: 1357dfd7

 ("platform/mellanox: Add TmFifo driver for Mellanox BlueField Soc")
Signed-off-by: Liming Sun <limings@nvidia.com>
Reviewed-by: Vadim Pasternak <vadimp@nvidia.com>
Reviewed-by: David Thompson <davthompson@nvidia.com>
Link: https://lore.kernel.org/r/8c0177dc938ae03f52ff7e0b62dbeee74b7bec09.1693322547.git.limings@nvidia.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>