REQUEST: Add support for QEMU SBSA

[PatrickRudolph]

To easily test ACPI changes within U-Boot add support for QEMU SBSA as well.

• https://github.com/qemu/qemu/blob/master/hw/arm/sbsa-ref.c
• https://github.com/ARM-software/arm-trusted-firmware/blob/master/docs/plat/qemu-sbsa.rst
• https://doc.coreboot.org/mainboard/emulation/qemu-sbsa.html

[PatrickRudolph]

first implementation:

• https://github.com/9elements/u-boot-acpi/commit/8eb68e61e42778148fbc38b9db423ffb5cc90435
• https://github.com/9elements/u-boot-acpi/commit/23f52539e5bed65ee73255071d96cb6572584848 Needs some cleanup.

[PatrickRudolph]

Feature complete with https://github.com/9elements/u-boot-acpi/commit/d52b3137065317603975f3820900172c5655f514 and https://github.com/9elements/u-boot-acpi/commit/e30d7adc5252ac353f1905469a07b74eab887f64