qfw: Add a subcommand to show QEMU arch-specific details

There are a few selectors in a different region which contain what seems
to be arch-specific information. Add a way to display this. So far it
only works on x86.

Signed-off-by: Simon Glass <sjg@chromium.org>

doc/usage/cmd/qfw.rst

@@ -16,6 +16,7 @@ Synopsis
     qfw cpus
     qfw load [kernel_addr [initrd_addr]]
     qfw table
+    qfw arch
 
 Description
 -----------
@@ -34,6 +35,8 @@ The *qfw table* command shows the instructions U-Boot uses to construct the
 ACPI tables. This is not as simple as a single blob of data, since some entries
 must be updated to take account of the address to which the tables are copied.
 
+The *qfw arch* command shows some items marked as 'arch local' in QEMU.
+
 kernel_addr
     address to which the file specified by the -kernel parameter of QEMU shall
     be loaded. Defaults to environment variable *loadaddr* and further to
@@ -150,6 +153,18 @@ This shows the *qfw table* command on an x86 target:
      14 add-ptr offset 10 size 4 dest 'etc/acpi/rsdp' src 'etc/acpi/tables'
      15 add-chksum offset 8 start 0 length 14 name 'etc/acpi/rsdp'
 
+
+This shows the *qfw table* command on an x86 target:
+
+::
+
+    => qfw arch
+    acpi tables = 0x00000000
+    smbios entrs= 0x00000000
+    irq0 overr  = 0x00000001
+    hpet        = 0x00000000
+
+
 Configuration
 -------------