MAINTAINERS: mark stmmac ethernet as an Orphan

I tried a couple of things to reinvigorate the stmmac maintainers
over the last few years but with little effect. The maintainers
are not active, let the MAINTAINERS file reflect reality.
The Synopsys IP this driver supports is very popular we need
a solid maintainer to deal with the complexity of the driver.

gitdm missingmaints says:

Subsystem STMMAC ETHERNET DRIVER
  Changes 344 / 978 (35%)
  Last activity: 2020-05-01
  Alexandre Torgue <[email protected]>:
    Tags 1bb694e 2020-05-01 00:00:00 1
  Jose Abreu <[email protected]>:
  Top reviewers:
    [75]: [email protected]
    [49]: [email protected]
    [46]: [email protected]
  INACTIVE MAINTAINER Jose Abreu <[email protected]>

Acked-by: Alexandre Torgue <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

MAINTAINERS

@@ -22500,11 +22500,8 @@ F:	Documentation/devicetree/bindings/phy/st,stm32mp25-combophy.yaml
 F:	drivers/phy/st/phy-stm32-combophy.c
 
 STMMAC ETHERNET DRIVER
-M:	Alexandre Torgue <[email protected]>
-M:	Jose Abreu <[email protected]>
 L:	[email protected]
-S:	Supported
-W:	http://www.stlinux.com
+S:	Orphan
 F:	Documentation/networking/device_drivers/ethernet/stmicro/
 F:	drivers/net/ethernet/stmicro/stmmac/