Drop the deprecated lm32 target

Target lm32 was deprecated in commit d849800512, v5.2.0.  See there
for rationale.

Some of its code lives on in device models derived from milkymist
ones: hw/char/digic-uart.c and hw/display/bcm2835_fb.c.

Cc: Michael Walle <michael@walle.cc>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210503084034.3804963-2-armbru@redhat.com>
Acked-by: Michael Walle <michael@walle.cc>
[Trivial conflicts resolved, reST markup fixed]

docs/system/deprecated.rst

@@ -198,14 +198,6 @@ from Linux upstream kernel, declare it deprecated.
 System emulator CPUS
 --------------------
 
-``lm32`` CPUs (since 5.2.0)
-'''''''''''''''''''''''''''
-
-The ``lm32`` guest CPU support is deprecated and will be removed in
-a future version of QEMU. The only public user of this architecture
-was the milkymist project, which has been dead for years; there was
-never an upstream Linux port.
-
 ``unicore32`` CPUs (since 5.2.0)
 ''''''''''''''''''''''''''''''''
 

docs/system/removed-features.rst

@@ -298,6 +298,13 @@ Nobody was using this CPU emulation in QEMU, and there were no test images
 available to make sure that the code is still working, so it has been removed
 without replacement.
 
+``lm32`` CPUs (removed in 6.1.0)
+''''''''''''''''''''''''''''''''
+
+The only public user of this architecture was the milkymist project,
+which has been dead for years; there was never an upstream Linux
+port.  Removed without replacement.
+
 System emulator machines
 ------------------------