mainboard/asus/p8x7x-series: Add new variant P8Z77-M

mainboard/asus/p8x7x-series: Add new variant P8Z77-M

Constructed out of a mix of autoport results, p8z77-m_pro, and
tool dumps.

Working:

- Core i7-3770K CPU
- SeaBIOS 1.13.0 boot to Linux 5.4.24 and Windows 10 1903
  (all further tests are under these versions)
- USB2 / USB3
- SATA
- Gigabit ethernet
- CPU temp sensors (memtest86+ 5.0.1)
- Hardware monitoring under Linux
- Native and MRC raminit
- PCIe GPU in both "PCIEX16" slots (16x/4x, nVidia Quadro 600)
- Integrated graphics with Intel OpROM and libgfxinit (all ports)
- Serial port
- Windows with libgfxinit framebuffer
- 2ch sound playback, Linux and Windows

Not working:

- PS/2 mouse
- 6ch analog audio out
- PCI POST card in PCI slot

Untested:

- PS/2 keyboard
- Internal USB3 ports
- Digital audio out

Change-Id: If756e791ddce747cb1706414be8e41e83f88922b
Signed-off-by: Keith Hui <buurin@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38988
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>