sun4m: Set HostID in NVRAM

On SparcStations, the HostID field in the NVRAM is equal to the last
three bytes of the MAC address (which is also stored in the NVRAM).

This constant is used as an identification/serial number on Solaris.

Signed-off-by: Olivier Danet <odanet@caramail.com>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
sun4m: fix slavio timer RUN/STOP bit

The sun4m architecture has one 'system' timer and one timer per CPU.
The CPU timers can be configured in two modes:

  * 22 bits Counter/Timer. Periodic interrupts.
  * 54 bits User timer. For profiling. In this mode, the Run/Stop bit
    controls the timer.

The run/stop bit controls the timer only when it is in "User" mode, but
its state shall be persistent.

Signed-off-by: Olivier Danet <odanet@caramail.com>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
sun4m: Add Sun CG3 framebuffer and corresponding OpenBIOS FCode ROM

The CG3 framebuffer is a simple 8-bit framebuffer for use with operating
systems such as early Solaris that do not have drivers for TCX.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
CC: Blue Swirl <blauwirbel@gmail.com>
CC: Anthony Liguori <aliguori@amazon.com>
CC: Peter Maydell <peter.maydell@linaro.org>
CC: Bob Breuer <breuerr@mc.net>
CC: Artyom Tarasenko <atar4qemu@gmail.com>
sun4m: Add Sun CG3 framebuffer initialisation function

In order to allow the user to choose the framebuffer for sparc-softmmu, add
-vga tcx and -vga cg3 options to the QEMU command line. If no option is
specified, the default TCX framebuffer is used.

Since proprietary FCode ROMs use a resolution of 1152x900, slightly relax the
validation rules to allow both displays to be initiated at the higher
resolution used by these ROMs upon request (OpenBIOS FCode ROMs default to
the normal QEMU sun4m default resolution of 1024x768).

Finally move any fprintf(stderr ...) statements in the areas affected by this
patch over to the new error_report() function.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
CC: Blue Swirl <blauwirbel@gmail.com>
CC: Anthony Liguori <aliguori@amazon.com>
CC: Peter Maydell <peter.maydell@linaro.org>
CC: Bob Breuer <breuerr@mc.net>
CC: Artyom Tarasenko <atar4qemu@gmail.com>