MAINTAINERS: net: mlxsw: Remove Jiri as a maintainer, add myself

Jiri has moved on and will not carry out the mlxsw maintainership duty any
longer. Add myself as a co-maintainer instead.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Acked-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/45b54312cdebaf65c5d110b15a5dd2df795bf2be.1638807297.git.petrm@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

MAINTAINERS

@@ -12180,8 +12180,8 @@ F:	drivers/net/ethernet/mellanox/mlx5/core/fpga/*
 F:	include/linux/mlx5/mlx5_ifc_fpga.h
 
 MELLANOX ETHERNET SWITCH DRIVERS
-M:	Jiri Pirko <jiri@nvidia.com>
 M:	Ido Schimmel <idosch@nvidia.com>
+M:	Petr Machata <petrm@nvidia.com>
 L:	netdev@vger.kernel.org
 S:	Supported
 W:	http://www.mellanox.com