mlxsw: pci: Remove unused values

Since commit f3a52c61

 ("mlxsw: pci: Utilize MRSR register to perform
FW reset") the driver no longer issues a reset via the PCI BAR, so the
offset of the reset bit is unused. Remove it.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>