uart: Add UART_ACPI_SPCR_CLASS

[andrew]

Summary

We don't care about most of acpi_uart_compat_data in the spcr code.
Split out the mapping from the SPCR interface type to uart class into
a new struct. This allows new SPCR interface types to be added that
don't have an entry in the DSDT, e.g. some PCI uarts may not.

Sponsored by: Arm Ltd

[jrtc27]

sys/dev/uart/uart_cpu_acpi.h

40

May make sense to flip these to recognise that cd_port_subtype is the key in this struct?

[jhibbits]

If it builds, it ships!

sys/dev/uart/uart_cpu_acpi.h

40

cd_port_subtype may be the key within the struct, but the iteration below iterates only over non-NULL cd_class.

[andrew]

sys/dev/uart/uart_cpu_acpi.h

40

I put it that way around so the padding is at the end rather than the middle of the struct.